风湿热的渗出性病理改变主要发生在（） A.心脏 B.关节 C.腱鞘 D.皮肤 E.大

点A（-4，5）关于x轴对称点B的坐标是______，关于y轴对称点C的坐标______．

It ____ for three hours and the ground is too wet toplay on, so the sports meet  _____.    [ ]

A. was raining;has been put off      

B. has been raining;has been put off        

C. has rained; put off      

D. has been raining;has put off

富水软弱破碎围岩隧道支护应符合哪些要求？

冻伤预防哪项不正确：（）。

A.注意保暖

B.皮肤涂擦防冻膏

C.适当按摩暴露皮肤

D.冻伤位置火烤

电弧电压越高，要求切割电源的空载电压（）

A.越高

B.越低

C.不变