韶山4型电力机车牵引拉杆装置采用的是（）。
A.平行牵引杆装置
B.中央斜单杆推挽式牵引杆
C.中间推挽式牵引杆
D.摆式连接装置
参考答案：B
用括号内所给单词的适当形式填空。
1. Sally's school orchestra is _____ (play) it.
2. What about _____ (listen) to the concert?
3. Mr. Wang is our English teacher, so he likes _____ (west) classical music.
4. His sister _____ (go) to America, hasn't she?
5. How many _____ (composer) are there in the hall?
大多数慢性肾衰竭患者高血压的主要原因是（）
A.血管紧张素工增高
B.血管紧张素Ⅱ增高
C.肾素水平增高
D.水钠潴留
E.高磷血症
(play) it.
merica, hasn't she?
er) are there in the hall?