————That was a green dinner. _______ 

————Thanks. But it really only took an hour.

A．I have never had it before.

B．I enjoyed it very much.

C．You must have spent all day cooking.

D．You must be tired.

心电图标准I导联时负极应连接（）。

A.左上肢

B.右上肢

C.左下肢

D.右下肢

E.胸前