Was it at the Olympic Games ______ were held this year ______ Liu Xiang got a metal?

A．which; that

B．which; which

C．that; when

D．when; that

关于采用工字钢钢拱架进行隧道支护的说法，错误的是()。

A.混凝土能充满钢拱架和围岩间空隙，钢拱架与喷射混凝土粘结好 

B.可用于混凝土内作为永久衬砌的一部分 

C.架设后能立即承载 

D.在V，VI级较软弱破碎围岩中使用较多