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

A.which

B.atwhich

C.fromwhich

D.inwhich

以下一国不能援引作为免除其国际责任的理由是（）。

A.同意

B.不可抗力和偶然事故

C.对抗措施

D.国家实行三权分立因而政府不干涉立法和司法机关