第34题: [单项选择]The country has already sent up three unmanned spacecraft, the most recent ______ at the end of last May. A. has been launched B. having been launched C. being launched D. to be launched 参考答案:B 答案解析:[解析] 考查独立主格结构。题干已有谓语,且这个句子的前后两部分是由逗号隔开的,因此逗号后面部分不能出现谓语动词,可排除A。C项表示正在被发射,D项表示将被发射,与后面的时间状语不符,也可排除。B表完