肿块消失的时间为出生后
A．2个月
B．4个月
C．6个月
D．5个月
E．3个月
参考答案：C
His father ______ for three days. [ ]
A. has be away from home
B. has been away from home
C. has leave home
D. has left home
第三周期元素中，最易与氢气反应生成气态氢化物的是[ ]
A．钠
B．硅
C．硫
D．氯
