肌萎缩侧索硬化最常见的首发临床症状是
A．手指运动不灵和力弱
B．延髓麻痹
C．四肢无力
D．大小便失禁
E．四肢肌张力增高
参考答案：A
I haven’t seen you since you came back from holiday. ________ a nice time?
A．Do you have
B．Did you have
C．Have you had
D．Had you had
制取较纯的一氯乙烷，用下列哪种方法最好
A．乙烷和氯气取代
B．乙烯加成氢气，再用氯气取代
C．乙烯和氯化氢加成
D．乙烯和氯气加成
