Condition sentence

If i have time, i will go
If my headache disappears, we can play cheers.
If today were Saturday, we could go to the beach.
If we did not have to study, we could go out tonight.
If he were sick, i would stay at home.
If i had not been in a hurry, i would not have spilled the milk.

Real conditions (possible true)
Future time:
if + subject + simple present ... + will / can / may / must + verb in simple form

If i have the money, i will buy a new car.
We will have plenty of time to finish the project before dinner if it is only ten o'clock now.

Habitual:
if + subject + simple present tense... + simple present tense....

John usually walks to school if he has enough time.

Command:
if + subject + simple present tense ... + command form*

If you go to the post office, please mail this letter for me.
Please cal me if you hear from Jane.

Unreal conditions (not true)
Present or Future time
if + subject + simple past tense ... + could / would / might + verb in simple form.

If i had the time, i would go to the beach with you this weekend.
He would tell you about it, if he were here.
If he did not speak so quickly, you could understand him.

Past time:
if + subject + past perfect ... + would / could / might + have + verb in past participle

If we had that you were here, we would have written you a letter.
She would have sold the house, if she had found the right buyer.
If he had not our way, we would have arrived sooner.

Had + subject + verb in past participle

Had i known that it was rain, i would have taken a rain coat.

As if / as though
Cấu trúc này chỉ ra điều không thật or đối lập sự thật vì thế nó tương tự như cấu trúc câu điều kiện. Động từ theo cấu trúc này phải là past tense or past perfect. Nhớ rằng động từ tobe của thì quá khứ là were không bao giờ là was.
subject + verb (present) + as if / as though +subject + verb(past)....

The older lady dresses as if it were winter ever in the summer.
Angelique walks as though she studied modeling.
He acts as though he were rich.

subject + verb(past)+ as if / as though + subject + verb (past perfect)....

Betty talked about the contest as if she had won the grand prize.
Jeff looked as if he had seen a ghost.
He looked as though he had run ten miles.