— I'm sorry I can't come to your party. I have to do my homework.

— ______. [ ]

A．That's all right

B．That is a good idea

C．It's good

D．That's too bad

据史书记载：“蜀守冰凿离碓，辟沫水之害，穿二江成都之中。此渠皆可行舟，有余则用溉浸，百姓飨其利。”材料中的“渠”指的是（）

A.郑国渠

B.灵渠

C.都江堰

D.“井渠”