4.2 课堂作业
Ⅰ.用所给单词的适当形式填空
1．Thousands of miles of good roads ________ (join) towns and countries.
答案：have joined
2．China ________ (make) great progress in science and technology.
答案：has made
3．All of you ________ (hear of) this many times.
答案：have heard of
4．We ________ (be) good friends since our middle school days.
答案：have been
5．It ________ (be) five years since he came here.
答案：has been
6．We ________ (study) English for six years.
答案：have studied
7．I ________ (receive) his letter two days ago.
答案：received
