We have received your letter of September 12，（）we are glad to know that you are interested in our electric heaters.

A.which

B.at which

C.from which

D.in which

电源线应走线方便，整齐，美观，与设备连接（），同时不应妨碍今后维护工作。

A.越长越好

B.越短越好

C.无所谓