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 4. Not only he but also we _____ right. He as well as we