醇溶液调pH法除鞣质的pH值为
A．pH5～6B．pH6～7C．pH7～8D．pH8～9E．pH9～10
参考答案：E
We have been on duty for four hours and ＿＿＿＿.
A．now comes your turn
B．now does your turn come
C．now your turn comes
D．comes now your turn
一号线地铁列车总风压低于680kpa时，（）个空压机将同时打风。
A.0
B.1
C.2
