— Do you often get online?
— Yes. I_______ lots of time on it. It's a good way to kill time.
A:cost
B:spend
C:take
D:use
关于导体中的电流与导体两端的电压的关系,下列叙述正确的是( )
下列算式中,计算结果为x2-3x-28的是( )