2016高考英语第一复习《高考英语复习--主谓一致和反意疑问句45题》从A、B、C、D四个选项中，选出可以填入空白处的最佳选项。
1. One-third of the area _____ covered with green trees. About seventy percent of the trees _____ been planted.
A. are; have B. is; has C. is; have D. are; has
2. The number of teachers in our college _____ greatly increased last term.
A number of teachers in this school _____ from the countryside.
A. was; is B. was; are C. were; are D. were; is
3. What _____ the population of China? One-third of the population _____ workers here.
A. is; are B. are; are C. is; is D. are; is
