一个点光源垂直入射到被照面上所形成的照度，与光源距被照面距离的几次方成反比（）？
A、一次方
B、二次方
C、三次方
D、四次方
参考答案：B
补全对话
A: Good morning, Sir. Can I help you?
B: 1 .
A: Yes, Sir. Which country would you like to visit?
B: 2 .I'm too tired and just want to relax.
A: Maybe you can spend your vacation in Switzer land. 3 .
B: But it's too cold. 4 .
A: What about Australia? There is a lot of sunshine there all the year round.
B: 5 And I can practice my English as well.
这种行为特征被称为是
A．A型性格B．B型性格C．C型性格D．D型性格E．E型性格
