Hangzhou Metro Line 1 , into use in 2012, is expected to relieve the heavy traffic in this city.y accepted by , 20113 years in
A. to be put
B. being put
C. having put
D. put
网友回答
A. to be put
B. being put
C. having put
D. put
解析：考查不定式用法。这条路线的投入使用是将来的事情，所以使用不定式表示将要发生的事情，两者之间又形成被动的关系，所以用过去分词表示被动。