一个圆柱的侧面展开图是正方形，它的底面直径与高相等。

如图所示，电源电压恒为6V，滑动变阻器R′的最大阻值为30Ω，当S闭合，滑片P在最右端时，电压表的示数为1.5V，则小灯泡L的电阻是____Ω，当滑动变阻器的滑片P移到a点时，电压表的实数为U_a，滑动变阻器的功率为P_a；再移动滑片P到b点时，电压表的示数为U_b，滑动变阻器的功率为P_b，若U_a：U_b=2：3，P_a：P_b=8：9，则滑动变阻器的滑片p在a，b两点时连入电路的电阻变化了____Ω（不计灯丝电阻随温度的变化）

动物细胞工程技术的基础是（　　）

 

阅读理解

    There is an old English saying. It tells us that we must go to bed early and get up early in the morning. Then we shall be healthy. We shall also be rich and clever. This is true. The body must have enough sleep to be healthy. Children of young age should have ten hours' sleep every night. Children who do not have enough sleep cannot do their work well and they may not be healthy.

    The body also needs exercise. Walking, running, jumping and playing games are all exercise. Exercise keeps the body strong.

    Exercise also helps the blood to move around inside the body. It is very important. Our blood moves to all parts of our body. The head also needs blood. Exercise helps us to think better.

已知集合 $A=\left\{x|\frac{x+3}{x-3}\le 0\right\}$ ，B={x|x﹣1≥0}，则A∩B为（   ）