由于MTO装置操作受再生烧焦主风量的限制，装置改造特将烟气双动滑阀的调节行程增大为（）mm。
A.220
B.200
C.180
D.170
参考答案：A
你能写出下列名词的复数形式吗?
1.hobby____
2.roll_____
3.frame_____
4.box_____
5.subject____
Is this the third time that you ________ late?
A．have been
B．am
C．was
D．had been
