密封装置内所需的封油压力降低的处理是（）
A.降低高位槽内的油面
B.回流控制阀开大
C.回流控制阀关小
D.降低高位槽高度
参考答案：C
The boy often forgets his homework. So his teacher is angry
A．does
B．to do
C．doing
D．did
简述甲状腺素中毒的表现和防治措施？
