下列重金属中导热性较差的是( )。
A．铝及铝合金
B．铜及铜合金
C．钛及钛合金
D．镍及镍合金
参考答案：D
It is a mainly dry country with only a few coastal areas that have ____ rainfall to support a large population．
A．desperate
B．stubborn
C．violent
D．adequate
药材人参主产于（）
A.河南
B.吉林、辽宁、黑龙江
C.甘肃
D.四川
E.广西、云南
