功率放大器处于多级放大器的（）。
A.输入级
B.中间级
C.输出级
D.任意一级
参考答案：C
喷淋式换热器属于板式换热设备。
For all the remaining items the stated dates of shipment are（）,but in no case would these dates be exceeded by ten days.
A.approximate
B.approximately
C.about
D.similar
