Mostofthetimeweareunawareofwhat

问题详情：

 Most of the time we are unaware of what ______ in our bodies; usually it is only when we get sick or feel pain that we notice.

A. happen                   B. happens                 C. is happening          D. has happened

【回答】

C

知识点：现在进行时及其被动式

题型：选择题