下列关于串联电路和并联电路的特点概括完全正确的一组是(   )

对于任意实数 $a$ ， $b$ ，定义关于“ $\otimes$ ”的一种运算如下： $a\otimes b=2a-b$ ．例如： $5\otimes 2=2\times 5-2=8$ ， $\left(-3\right)\otimes 4=2\times \left(-3\right)-4=-\mathrm{10。}$

集合A={x∈N|0＜x＜4}的真子集个数为（   ）

2015年的政府工作报告首次提到“创客”。 “创客”热衷于创新，善干发现问题并提出解决方案，通过创意、设计、制造提供各种产品和服务。要成为“创客”．青少年就要(    )

A增强创新意识．投身创新实践

B放弃学业，在家从事科技发明

C积极实施创新驱动发展战略

D认真学习现代科学技术知识，培养艰苦创业精神

    Welcome to England! The weather of England often changes. It can be rainy, sunny, cloudy, windy, warm, foggy or cold at any time of year. If it's raining when you get up in the morning, it can be hot and sunny in the afternoon.

    In England, shops are usually open from 9:00 in the morning to 5:30 in the afternoon. On Sundays some shops are open from 10:00 a. m. to 4:00 p. m. But most shops are closed. Banks, museums（博物馆）or other places are open from 10:00 a. m. to 5:00 p. m. You can go to the parks at any time.

    All the cities have buses, trains and taxis（出租车）. People wait in line (排队等候) for buses and they will not be happy if you come to the front from the end of the line. Don't forget that, traffic goes on the left.

Be careful and enjoy your time here.

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