-----Did your father come back early last night?

-----Yes ,It was not yet eight o’clock _____he arrived home.

A．before

B．when

C．that

D．until

锅炉点火前，应检查照明情况，保证水位计有足够的（）。

A.水位

B.光线

C.光线和亮度

D.亮度寸