气动差压变送器中，当测量力矩与反馈力矩相平衡时，主杠杆处于平衡状态，喷嘴与挡板的距离也就一定，这时就有一个与差压相应的气压输出。
参考答案：对
—What did Yang Ying say?
—She said they _____ a school trip the next weekend. [ ]
A. will have
B. had
C. would have
D. have
开拓煤量的可采期一般为（）。
