液压控制阀的特点就是通过改变连通关系和阀口通道面积来进行控制和调节的。
参考答案：对
—Who is ______ man with glasses?
—Oh, he's our new English teacher, Mr Li. [ ]
A. a
B. an
C. the
D. /
I have two pairs of shorts. _____ are nice.[ ]
A. Shorts
B. It
C. These
D. They
