－The lady is really young and fashionable. Do you think so?

－     , she has four children.

A．What’s worse

B．Believe it or not

C．In a word

D．That’s to say

当焊接热导率高的原材料（如铝、铜）时，可以考虑选用有较高热穿透性的（）。

A、氩气

B、氮气

C、氦气