金属及合金的主要物理性能有比重、熔点、导热性和导电性等。
参考答案：对
---- What about going swimming this afternoon , Tom?
---- ____. I have a test tomorrow, so I have to go over my lessons today.
A．I’d like to
B．I’ll take it
C．I’d rather not
D．I don’t think so
为什么需要打开汽车水箱盖时，必须待发动机冷却后进行？
