更换管路时严禁停风作业。
参考答案:错
反渗透、超滤和微孔过滤在原理、设备构造和运行上有何区别?有何联系?
—We can use QQ to talk with each other on the Internet.
—Really? Hut can you tell me ______ use it? [ ]
A. how I can
B. how can I
C. what I can