来自崔忠升的问题
Everyoneofusshouldkeeptheclassroom___everyday.A.cleanb.cleanedc.cleaningd.toclean为什么不是C?Keepdoing=一直保持在某个状态
Everyoneofusshouldkeeptheclassroom___everyday.
A.cleanb.cleanedc.cleaningd.toclean
为什么不是C?Keepdoing=一直保持在某个状态
