IF CONDITIONAL

Conditional tenses are used to speculate about what could happen, what might have happened, and what we wish would happen. In English, most sentences using the conditional contain the word if. Many conditional forms in English are used in sentences that include verbs in one of the past tenses. This usage is referred to as "the unreal past" because we use a past tense but we are not actually referring to something that happened in the past. There are five main ways of constructing conditional sentences in English. In all cases, these sentences are made up of an if clause and a main clause. In many negative conditional sentences, there is an equivalent sentence construction using "unless" instead of "if".

Conditional sentence type	Usage	If clause verb tense	Main clause verb tense
Zero	General truths	Simple present	Simple present
Type 1	A possible condition and its probable result	Simple present	Simple future
Type 2	A hypothetical condition and its probable result	Simple past	Present conditional or Present continuous conditional
Type 3	An unreal past condition and its probable result in the past	Past perfect	Perfect conditional
Mixed type	An unreal past condition and its probable result in the present	Past perfect	Present contditional

The zero conditional

The zero conditional is used for when the time being referred to is now or always and the situation is real and possible. The zero conditional is often used to refer to general truths. The tense in both parts of the sentence is the simple present. In zero conditional sentences, the word "if" can usually be replaced by the word "when" without changing the meaning.

If clause	Main clause
If + simple present	simple present
If this thing happens	that thing happens.
If you heat ice	it melts.
If it rains	the grass gets wet.

Type 1 conditional

The type 1 conditional is used to refer to the present or future where the situation is real. The type 1 conditional refers to a possible condition and its probable result. In these sentences the if clause is in the simple present, and the main clause is in the simple future.

If clause	Main clause
If + simple present	simple future
If this thing happens	that thing will happen.
If you don't hurry	you will miss the train.
If it rains today	you will get wet.

Type 2 conditional

The type 2 conditional is used to refer to a time that is now or any time, and a situation that is unreal. These sentences are not based on fact. The type 2 conditional is used to refer to a hypothetical condition and its probable result. In type 2 conditional sentences, the if clause uses the simple past, and the main clause uses the present conditional.

If clause	Main clause
If + simple past	present conditional or present continuous conditional
If this thing happened	that thing would happen. (but I'm not sure this thing will happen) OR that thing would be happening.
If you went to bed earlier	you would not be so tired.
If it rained	you would get wet.
If I spoke Italian	I would be working in Italy.

Type 3 conditional

The type 3 conditional is used to refer to a time that is in the past, and a situation that is contrary to reality. The facts they are based on are the opposite of what is expressed. The type 3 conditional is used to refer to an unreal past condition and its probable past result. In type 3 conditional sentences, the if clause uses the past perfect, and the main clause uses the perfect conditional.

If clause	Main clause
If + past perfect	perfect conditional or perfect continuous conditional
If this thing had happened	that thing would have happened. (but neither of those things really happened) OR that thing would have been happening.
If you had studied harder	you would have passed the exam.
If it had rained	you would have gotten wet.
If I had accepted that promotion	I would have been working in Milan.

Mixed type conditional

The mixed type conditional is used to refer to a time that is in the past, and a situation that is ongoing into the present. The facts they are based on are the opposite of what is expressed. The mixed type conditional is used to refer to an unreal past condition and its probable result in the present. In mixed type conditional sentences, the if clause uses the past perfect, and the main clause uses the present conditional.

If clause	Main clause
If + past perfect or simple past	present conditional or perfect conditional
If this thing had happened	that thing would happen. (but this thing didn't happen so that thing isn't happening)
If I had worked harder at school	I would have a better job now.
If we had looked at the map	we wouldn't be lost.
If you weren't afraid of spiders	you would have picked it up and put it outside.

source :  http://www.edufind.com/english-grammar/conditional/

ADJECTIVE CLAUSE & NOUN CLAUSE

ADJECTIVE CLAUSE

What Is an Adjective Clause? (with Examples)

When we think of an adjective, we usually think about a single word used before a noun to modify its meanings (e.g., tall building, smelly cat, argumentative assistant). However, an adjective can also come in the form of an adjective clause.

An adjective clause usually comes after the noun it modifies and is made up of several words which, like all clauses, will include a subject and a verb.

Examples of Adjective Clauses

Here are some examples of adjective clauses:

·         The carpets which you bought last year have gone moldy.

·         The film which you recommended scared the kids half to death.

·         The follies which a man regrets most in his life are those which he didn't commit when he had the opportunity. (Helen Rowland, 1876-1950)

·         Bore: a person who talks when you wish him to listen.

The Components of an Adjective Clause

An adjective clause (which can also be called an adjectival clause or a relative clause) will have the following three traits:

·         It will start with a relative pronoun (who, whom, whose, that, or which) or a relative adverb (when, where, or why).

(This links it to the noun it is modifying.)(Note: Quite often, the relative pronoun can be omitted. However, with an adjective clause, it is always possible to put one in. There is more on this below.)

·         It will have a subject and a verb.

(These are what make it a clause.)

·         It will tell us something about the noun.

(This is why it is a kind of adjective)

The Relative Pronoun Can Be Omitted

It is common for the relative pronoun to be omitted. Look at these examples:

·         The carpets which you bought last year have gone moldy. 

·         The film which you recommended scared the kids half to death. 

·         The follies which a man regrets most in his life are those which he didn't commit when he had the opportunity.  (Helen Rowland, 1876-1950) 

Commas or No Commas around an Adjective Clause?

The big question with an adjective clause is whether to offset it with commas or not. The rule is this:

·         Don't use commas if your clause is essential; i.e., it is required to identify its noun. (This is called a restrictive clause.)

·         Do use commas if your clause is just additional information. (This is called a non-restrictive clause.)
This is a good test: If you would happily put brackets around it or delete it, then use commas.

Here is an example of a non-restrictive clause:

·         My brother, who claimed to have a limp, sprinted after the bus. 

(This clause is not required to identify My brother. It is just additional information.)

·         My brother (who claimed to have a limp) sprinted after the bus. 

(As it's just additional information, you can put it in brackets.)

·         My brother sprinted after the bus. 

(As it's just additional information, you can even delete it.)

NOUN CLAUSE

What Are Noun Clauses? (with Examples)

A noun clause is a clause that plays the role of a noun. For example (noun clauses shaded):

·         I like what I see.

·         I know that the tide is turning.

·         I've met the man who won the lottery.

(Not all agree this is a noun clause. See Note on the right.)

Compare the three examples above to these:

·         I like cakes.

·         I know London.

·         I've met Madonna.

The words in bold are all nouns. This shows that shaded clauses in the first three examples are functioning as nouns, making them noun clauses.

Like any noun, a noun clause can be a subject, an object, or a complement.

In a sentence, a noun clause will be a dependent clause. In other words, a noun clause does not stand alone as a complete thought.

Examples of Noun Clauses

Here are some examples of noun clauses:

·         A person who trusts no one can't be trusted. (Jerome Blattner)

(This noun clause is the subject of the sentence.)
(Not all agree this is a noun clause. See Note on the right.)

·         That he believes his own story is remarkable. (Jerome Blattner)

(This noun clause is the subject of the sentence. Be aware that starting a sentence with a noun clause starting That is acceptable, but it grates on lots of people's ears. As a result, many writers prefer to precede it with "The fact…".)

·         Ask your child what he wants for dinner only if he's buying. (Fran Lebowitz)

(This noun clause is the direct object of ask.)

·         He knows all about art, but he doesn't know what he likes. (James Thurber, 1894-1961)

(This noun clause is the direct object of know.)

·         It is even harder for the average ape to believe that he has descended from man. (H L Mencken, 1880-1956)

(This noun clause is the direct object of believe.)

·         I never know how much of what I say is true. (Bette Midler)

(This noun clause is an object of a preposition.)

·         Man is what he eats. (Ludwig Feuerbach)

(This noun clause is a subject complement.)

·         My one regret in life is that I am not someone else. (Woody Allen)

(This noun clause is a subject complement.) 

·         An economist is a man who states the obvious in terms of the incomprehensible. (Alfred A Knopf)

(This noun clause is a subject complement.)
(Not all agree this is a noun clause. See Note on the right.)

Source : http://www.grammar-monster.com/glossary/adjective_clauses.htm

              http://www.grammar-monster.com/glossary/noun_clauses.htm