if后的时态

　　例句

　　1.She gets very upset if I exclude her from anything

　　要是有什么事情我不让她参加，她会非常难过。

　　2.He asked if I had left with you, and I said no

　　他问我是否和你一块儿离开的，我说不是。

　　3.Sometimes, that standard is quite difficult, if not impossible, to achieve

　　有时即便有可能达到那个标准，那也是非常困难。

　　4.If I could just make another small point about the weightlifters in the Olympics

　　请允许我就有关奥运会举重运动员的问题再补充一点。

　　5.I wonder if you'd be kind enough to give us some information, please?

　　请问您能不能给我们提供一些信息？