串级调节系统中,主调节器起()作用,一般采用PI或PID调节规律。
A、粗调
B、细调
参考答案:B
We still couldn’t decide _________ with our difficulties in learning English.[ ]
A.how to do
B.how to deal
C.what to deal
D.what to solve
固定网短消息的存储有效期≥多少小时?()
A.24小时
B.36小时
C.72小时
D.84小时