If he is late, we will have to go without him.
2.
If I become president, I will change the social security system.
3.
If I became president, I would change the social security system.
4.
If we win this match, we are qualified for the semifinals.
5.
If my mother knows about this, we are in serious trouble.
6.
If I had taken an aspirin, I wouldn't have a headache now.
7.
If you had warned me, I would not have told your father about that party.
8.
If I find her address, I’ll send her an invitation.
9.
If I found her address, I would send her an invitation.
10.
If I had found her address, I would have sent her an invitation.
11.
If I weren't flying to Detroit, I would have planned a trip to Vancouver.
12.
If I were taking this exam next week, I would be high-strung.
13..
I would have been happy to help you if I wasn't in the middle of another meeting.
14.
If the elephant wasn't in love with the mouse, she'd have trodden on him by now.
15.
If I was a good cook, I'd have invited them to lunch.
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