大闸手柄在制动区其减压量不准确是因为凸轮各位间的（）不正确或调整阀凸轮支承（）。
参考答案：降程；磨耗
-- I am going to Sidney for further studies next month.
-- That’s fantastic. Can you keep emailing me ______ you are there?
A．though
B．because
C．until
D．while
储存了油气的储集层称为含油气层，已开发的含油气层称为产层。
