负伤率是指平均每（）名职工中的伤亡人数。
A.百
B.千
C.万
D.十万
参考答案：B
When his mother came into his room, he pretended ______ .[ ]
A. to asleep
B. sleeping
C. slept
D. to be asleep
下列哪些疾病与痛经无关()
A．子宫内膜异位症
B．子宫腺肌瘤
C．月经频发
D． * * 痉挛
E．盆腔炎
