It was in the lab, ________ was taken charge of by Professor Curie, _______ they did the experiment.

A．where; that

B．that; that

C．which; that

D．which; where

建设工程合同签订的步骤，在法律上分解为（）两个环节。

A.要约与履约 

B.要约与承诺 

C.承诺与履约 

D.违约与履约