一般情况下，可摘局部义齿固位体的数目应（）
A.尽可能多
B.4～6个
C.2～4个
D.1～2个
E.尽可能少
参考答案：C
When I got home, my parents _____ for about an hour.[ ]
A. has got back
B. has gone back
C. had come back
D. had been back
食管癌的晚期症状有（）
A.吞咽困难
B.声音嘶哑
C.呕吐
D.锁骨上淋巴结肿大
E.胸背疼痛
