Question

【题目】China's high-speed trains _________ and perfected now.
A.developed
B.have developed
C.are being developed
D.will have been developed

Answer 1

【答案】C
【解析】句意：中国的高速列车现在正在发展和完善。根据now可知用现在进行时，train与develop构成被动关系，故用现在进行时的被动语态：is/are being+过去分词，所以选C。