涂料是保护坩埚、工具、浇包、模具等不被合金粘结，防止它们的成分渗入或污染合金液。
参考答案：对
______ is impossible if you put your heart into it.
A．Anything
B．Something
C．Everything
D．Nothing
风湿性心脏炎最常见侵犯的部位（）
A.心包膜
B.二尖瓣膜
C.三尖瓣膜
D.主动脉瓣膜
E.肺动脉瓣膜
ou put your heart into it.