一般现在时shall/will + 动词原形
If he comes, he will bring his violin.
The volleyball match will be put off if it ___.
A. will rain
D. is rained
1）在真实条件句中，主句不能用be going to表示将来，该用shall, will.
(错) If you leave now, you are never going to regret it.
(对) If you leave now, you will never regret it.
2）表示真理时，主句谓语动词便不用shall (will) +动词原形，而直接用一般现在时的动词形式。
一般过去时should( would) +动词原形
If they were here, they would help you.
过去完成时should(would) have+ 过去分词
If she had worked harder, she would have succeeded.
The rice would not have been burnt if you had been more careful.
If my lawyer had been here last Saturday, he would have prevented me from going.
If he had come yesterday, I should / would have told him about it.
含义：He did not come yesterday, so I did not tell him about it.
If he had not been ill and missed many classes, he would have made greater progress.
含义：He was ill and missed many lessons, so he did not make greater progress.
were+ 不定式would + 动词原形