在启动中心收件箱中有（）个标签页选项，可供使用。
A.1
B.2
C.3
D.4
参考答案：C
The retired teacher is said to have returned from the USA, where he ______ by some of his old students.
A．would be visited
B．visited
C．had been visited
D．have been visited
27岁初产妇，妊娠32周，近半个月来胎动消失，体重下降，为明确诊断首选下列哪项检查（）。
A.腹腔镜
B.宫腔镜
C.羊膜镜
D.B超
E.腹部X线
