if后面怎么不用现在分词做了一个关于现在分词的题目whileiwaswaitingatthedoctor's,ireadthewholeofashortstory.可以换成whilewaitingAfteryouhaveusedthebruseh,putitinitsproperplace分句可以换成after

Question

if 后面怎么不用现在分词
做了一个关于现在分词的题目
while i was waiting at the doctor's,i read the whole of a short story.可以换成 while waiting
After you have used the bruseh,put it in its proper place 分句可以换成 after using the brush
if you work hard,you will succeed.
为什么不用if working hard,you will succeed 而只是用 working hard,you will succeed?
刚才edwardswift 说的有一点道理。不过
while he worked,he sang 可以改成while working,he sang.这里的while 也不是介词啊，怎么也对呢

Answer 1

应该改为
Work hard,and you will succeed.
这个句子省略了if.其实就相当于
If you work hard,you will succeed.
句型：祈使句,+and .= IF ...,...