江涛想探究凸透镜成像规律.实验桌上有两个凸透镜,焦距分别为10cm和20cm.
如图,已知点B,E,C,F在一条直线上,AB=DF,AC=DE,∠A=∠D.
A man says to his friend,"Guess how many coins(硬币) I have in my pocket(兜). "
The friend says. "If(如果) I guess right,will you give me one of them?"
The man says,"If you guess right,I'll give you both(两个都) of them. "
一 Don't you think it is ______ for us to read everyday?
一 Yeah. Reading can make us smart.