买3本笔记本,付出20元,找回8元,每本______元.
(20-8)÷3
=12÷3
=4(元)
答:每本4元.
故答案为:4.
When Peter speaks in public, he always has difficulty ______ the right things to say.
A.thinking of
B.to think of
C.thought of
D.think of
功率放大器的主要作用是()。
A.对大信号进行放大,使负载获得足够大的功率
B.对小信号进行放大,使负载获得足够大的功率