白炽灯泡亮时和熄灭时，灯丝的电阻大小是：[ ]

A.熄灭时大

B.点燃时大

C.一样大

D.不能确定

Time is money! We should（）our time.

A.be fit for

B.make good use of

C.play a part of

D.take the place of