II. The present perfect tense.
1Our teachers have explained the English grammar.
2The students have discussed the pollution problems since last week.
3Have the thieves stole the most valuable painting in the national museum?
4Have you finished the above sentences?
5They have given Tom a present.
6The weather has turned all the leaves yellow.
7A famous writer has written that book.
8I have just bought a new pen.
9They have awarded the best student a scholarship.
10They have already reported the result of the exam.
11They have sold thousands of CD machines since 1983
12He has broken his ankle in a football match.
????????