It's your duty__the classroom___.A to keep ,clean B to keep ,cleaning
问题描述:
It's your duty__the classroom___.A to keep ,clean B to keep ,cleaning
C keep,clean D for keeping ,clean
答
A保持教室干净整洁是你的义务. 此处是It 做形式主语的用法 It is .+to不定式同时keep+sth+adj.形式中宾语补足语应该为形容词adj.形式