--- Where did you spot the murderer?

--- It was in the cinema __________ we watched Tran formers that I saw him. I can’t remember when.

A．that

B．when

C．where

D．on which

排水管渠的圆形断面的优点包括______。

A．较好水力性能

B．水力半径大

C．流速大

D．通过的流量小