--The classroom is __________ clean __________ it was yesterday.

--Sorry, I forgot to clean it.

A．as; as

B．so; as

C．not so; as

D．more; than

下列选项中，属于个人商务贷款业务担保方式的是（）。

A.个人房产抵押

B.存单质押

C.保证人保证

D.股权质押