if＋so：“如果这样的话”

If so, find out what would need to change.

如果是这样，请找出需要改变的事项。

Do you love life? If so, don't waste it, because it consists of time.

你热爱生命吗？如果是就别浪费生命，因为它是由时间组成的。

if＋not：“要不, 不然”

Where should I go, if not to your house?

我不到你家里去, 到哪里去呢?

I might see you tomorrow. If not, it'll be Saturday.

我可能明天去看你。如果不是明天，那就是周六。

if＋ever：通常与seldom连用，表示“极少”“难得”

His children rarely, if ever, see him at his place of work.

孩子们很少在父亲的工作地点看到他。

He seldom if ever travels abroad.  

他到国外旅行，即使有过，也是极少的。

if＋代词：构成if any“如果真有的话; 如果你有的话”，if anything“如果是这样的话（之前多已提及相反的情况）”, if anyone等

There are few, if any, mistakes in the book.

那本书里即使真有错误, 也不多。

I haven't made much of this—if anything, I've played it down.

对此我并没有加以重视—— 如果是这样的话，那我是看低它了。

If anyone, he knows. 如果有人知道，那就是他了。

if＋形容词：if necessary“如必要的话”，if possible “如果可能的话”

I'll help you, if possible.

如果可能的话, 我会帮助你。

You can use these reference books, if necessary.

如果必要，你可用这些参考书。

if＋过去分词：if与分词之间省略了主语和be，即状语从句的省略

He will come if asked.= He will come if he is asked. 他如被邀就会来。

练习：

1. Every evening after dinner, if not _____ from work, I will spend some time walking my dog.

A. being tired  B. tiring       C. tired        D. to be tired

2. -----Have you got any particular plans for the coming holiday?

----- Yes, _______, I'm going to visit some homes for the old in the city.

A. If ever      B. If busy  C. If anything       D. If possible

3. Some of you may have finished unit one. _____ , you can go on to unit two.

A. If you may      B. If you do      C. If not       D. If so

4. We all know that, __________, the situation will get worse.

A. not if dealt carefully with           B. if not carefully dealt with

C. if dealt not carefully with           D. not if carefully dealt with

5. Though he started late. Mr. Guo played the piano as well as,if _______ ,Miss Liu.

A．not better than B．not better           C．no better than      D．better

6. The experiment shows that proper amounts of exercise, if ____ regularly, can improve our health.

A. being carried out      B. carrying out   C. carried out      D. to carry out

7. It sounds like something is wrong with the car's engine. _____ , we'd better take it to the garage immediately.

A. Otherwise    B. If not    C. But for that    D. If so

================  答案及来源 ===================

1.C 09湖南    2.D 08安徽   3.D 09江西  4.B 07全国1   5.A 07陕西

6.C 10浙江    7.D 11江苏