国库单一账户与财政部门在商业银行开设（）进行支付清算。

A.财政专户

B.零余额账户

C.预算单位零余额账户

D.特设专户

— Can you see _____?

— No. Let's go and have a look. Maybe we can help them.[ ]

A. what was going on there

B. what are they doing there

C. what were they doing there

D. what is going on there