During holidays，Kitty usually goes to see the exhibits in many museums，such as the history museum，the art museum，the museum of science and technology and the museum of natural history．There are thousands of wonderful things in museum.There are paintings，sculptures(雕塑)，costumes(服饰)，swords(剑)，ancient animal bones and plants，stuffed animals(动物标本)and many others．It is always a good review of history to visit those museums．It is also a great way to learn more things by myself．

恩格斯说：“我们不要过分陶醉于对自然界的胜利。对于我们的每一次胜利，自然界都报复了我们。”下列人类所面临的诸多问题中能佐证这一观点的是（      ）

—Why not stop ______ a rest?

  —Oh, it's so exciting that I can't stop ______ the kite.

同学在测标有“2.5V”字样的小灯泡功率实验时，他的电路已经连成如下图甲所示．