km，m，mm，dm
He was in hospital for six months. He felt as if he were ______ from the outside world.[ ]
A. cut down
B. cut off
C. cut in
D. cut through
第一触角长，与吻愈合呈尖突状不能活动的是（）。
A.蚤状溞
B.象鼻溞
C.秀体溞
D.裸腹溞
