液压阀根据用途不同可以分为压力控制阀、流量控制阀和()。
A.伺服阀
B.比例阀
C.方向控制阀
D.插装阀
参考答案:C
The fact that too many advertisements are _____ in TV programs has upset most TV viewers.
A.surrounded
B.carved
C.inserted
D.circulated
结构简单的管状铸件大批量生产一般采用刮板造型。