常见的句式有：(1)It is +形容词(of sb)to do sth.(2)It is +名词(for sb)to do sth.(3)It takes sb some time to do sth.(4)It is +形容词(for sb)to do sth.句式(1)中常用nice,kind,clever,good,right,wrong,foolish,careless等形容词，与介词of搭配，这些形容词常表述不定式逻辑主语的属性或性质；句式(4)中常用hard,difficult,easy,important等形容词，与介词for搭配，表示不定式表示的动作、行为的性质。
1.He wants ______ some vegetables.
A.buy B.buying C.to buy D.buys (山西省)
2.Don't forget ______ your homework with you when you come to school.
2.——Why didn't you buy some bread on your way home?
——Sorry, I forgot ______ some money with me.
A.take B.taking C.to take D.took (湖北省)
3.——Let's have a rest, shall we?
——Not now, I can't stop ______ the letters.
A.write B.to write C.writing D.and write (湖北省)
4.Jim was badly hurt, so he had to stop ______ (walk).(用所给单词的正确形式填空)(四川省)
Key：1.A 2.C 3.C 4.walking
【解析】一些常见的动词后面接不定式和接动词的-ing形式的区别如下：＂stop to do sth＂意为＂停止正在做的事情去做另外一件事＂，＂stop doing sth＂意为＂停止正在做的事＂：＂remember to do sth＂意为＂记住去做某事＂(事还未做)，＂remember doing sth＂意为＂记得做过某事＂(事已做)：＂go on to do sth＂意为＂接着做某事＂(做完一事，接着做另一事)，＂go on doing sth＂意为＂继续做某事＂(一事未做完接着往下做)：＂forget to do sth＂意为＂忘了做某事＂(事还未做)，＂forget doing sth＂意为＂忘了曾做过某事＂(事已做)。
5.When I was walking in the street I saw a plane ______ over my head.
A.flies B.flying C.flew D.to fly (福建省)
6.A woman saw it ______ when she was walking past.