As if vs. As though

As if and as though are two conjunctions that introduce subjunctive and indicative sentences.
They can be interchanged in many occasions. So they mean the same:
If something happens as if/as though something else were true, it happens in a way that it reminds you of it.

They have three definitions:
1- In a way that suggests something is true.

- Brian shook his head as if to say:"don't trust her"
- You look as if you 're having a good time.
- He looked at me as though defying me to argue.

2- In a way that indicates something is unlikely and should not be considered.

- He looked at me as if I was mad.
- He ran as though ghosts were chasing him.
- I got treated as if I was brainless.

3- They mean that when they come with such verbs as:"seem,appear,look,feel,sound"

- It seemed as if the day would never end.
- She sounds as if she's really sick.
- I felt as though all my strength had gone.

Learners' common errors

1- Many people regard it as incorrect to use was instead of were in this type of sentences.
Were or was(more common) both can be used in conversation but in formal style were is preferred.

- She talked if she was rich.

2- One of the most frequently asked questions is the tense of sentences and its usage in this instruction.
We can use a past tense with a present meaning after as if/as though indicating that a comparison is unreal.

- He talks as if he's our boss.
- He talks as if he was our boss.

The first sentence shows that he may be our boss. The second sentence,whereas indicates he is not our boss.

As if / As though +present Tense

A- He acts as if he doesn't know me.(At the present time, He really doesn't know me.)

As if / As though +Past Tense

B- He acts as if he didn't know me.( At the present time, He pretends that he doesn't know me or I'm not not sure whether he knows me.)

As if / As though +Past Perfect

Although There are conflicting arguments about the form of as if and some people regard it as incorrect to use it and some other believe there is no difference between this and the previous construction -B, some think that it is used for unreal situations and some maintain that it is used in both real and imaginary occasions,however we consider the likeliest usage which is the following definition for this use of as if :
- If we talk about a hypothetical past situation, the past perfect tense is used.
C- He acted as if he hadn't know me.(He pretends that he doesn't know me, but I know you do)
- He seems as if he hadn't slept for days.(He seems not to have slept for days, but I know he has.).
Note that this structure is like the former two ones is present tense.

Past Tense + as if /as though + Past Tense

D- He acted as if he didn't know me.( In the past, he didn't really know me)

Past Tense + as if /as though + Past Perfect

E- He acted as if he hadn't known me.( In the past , he pretended that he hadn't known me or may be he hadn't known me.).

3- The use of as if or as though sometimes is a matter of collocation.In many cases both can be interchangeably used but sometimes for the reason of collocation, one is preferred to the other one,for example in the following sentence as if is more common than as though,although the latter is not grammatically incorrect.

- He acts as if he doesn't know me.
- You turn on the television and look through the list of new movies, as if you have a video store in your home.Y

As if/As though can:

4- be associated with adverbs or adjectives:

- After asking her age, she stood a moment, as if embarrassed.
- She moved her leg,as though in pain.
- He fell over backwards and lay,as if struck by lightning.
- Garin shot him a dark glance, as though in warning.
- Jill crossed her legs and rested her chin on one fist,as if lost in deep thought.
- The crowd suddenly silenced, as if by magic.

5- come with ing and infinitive forms.

- He paused and cocked his head,as if listening.
- He ran off to the house, as though escaping.
- She pursed her lips together,as though fearing to betray her news.
- Albert opened his mouth as if to protest.
- He step forward as though to kiss his mother.

6- can be associated with a preposition:

- She was trembling as if with fear.
- He leaned against his father as though for support.

7- may be placed at the beginning of a sentence.

- As if to remind him,the church clock struck eleven.
- As if we don't belong to ourselves?