It was several minutes before I was            of what was happening.      [ ]

A．know                    

B．realize      

C．wear                    

D．aware

杆塔及拉线基坑的回填应设防沉层，防沉层的上部不得小于坑口，其高度视夯实程度确定，并宜为（）mm。

A.150～200；

B.200～300；

C.300～500；

D.400。