Question

A lot of new schools________since 1991．

1. A.
   have opened
2. B.
   have been opened
3. C.
   opened
4. D.
   have been open

Answer 1

B
分析：由since199l可知用现在完成时，open在句中的意思是“开办”，为及物动词，“开办”的宾语“学校”成了句子的主语，因此要用现在完成时的被动语态B项。