A:初春,冰雪消融汇成溪流
B:盛夏,烈日炎炎土地干涸
C:深秋,清晨草地出现白霜
D:严冬,寒风凛冽湖水结冰
看图片完成对话。
A: When is your birthday?
B: My birthday is on____.
A: What will you do on your birthday?
B: I'll ____.
A: Cool! When is your mother's birthday?
B: It's on____.
A: What will you do for your mother?
B: I'll____.(为她做蛋糕)
A: Great!
如图甲是“探究串联电路电流特点”的实验电路图.
下列关于实验室用高锰酸钾制取氧气的说法正确的是
如图所示,在凸透镜的右焦点处有一平面镜垂直于主光轴放置.一束光AB经凸透镜和平面镜怎样传播?画出光路图来.