a number of problems ----to be solved though we have had the meeting.
问题描述：
a number of problems ----to be solved though we have had the meeting.
a remain b remained c left d leave 为什么不选 d ,而选a
答
问题遗留下来是一种被动态,是被留下来不可能是问题自己主动留下来,所以即使用leave也应该是被动态 left ,而问题仍在一般是用remain 的