I had no clue what he was trying to suggest because he just couldn't （） the subject.
A、keep to
B、keep up with
C、keep off
D、keep out of
【正确答案】：A
【题目解析】：本题考查动词短语辨析。keep to：坚持，遵守，固守（习惯等）；keep up with：赶得上，和…保持联系；keep off：让开，不接近，避开某一话题；keep out of：躲开，置身…之外。根据后面的subject可以判断，四个选项中A选项最符合题意。句意：我不知道他想暗示什么，因为不能围绕一个主题来讲。
