处于青春期的我们,时常迷茫烦恼,甚至有时自己都不认识自己。现在请你静心思考,以下观点正确的是( )
①青春期生理上的巨变也会造成心理上的波动
②正确看待青春期的萌动心理, 坚持正确的男女同学交往原则
③青春期要通过自我评价、比较评价、他人评价 等方式来正确认识自己、完善自己
④青春期的我们已经完全独立,不再需要父母和老师的帮助
A:①②④
B:①②③
C:②③④
D:①③④
①北极地区是陆地
②南极地区是陆地
③北极地区被三大洋包围
④南极地区被三大洋包围
Inventions make the world better, smarter and a little more fun.
The folding bike helmet (头盔)
People hate to wear a helmet because it's thick and heavy. Morpher is a bike helmet made from plastics. It is just as strong as the traditional ones, but flexible (灵活的) enough to fold almost totally flat. Also it is much easier to carry.
Shoes that tie themselves
After we see the movie Back to the Future, almost everyone wants a pair of self-tying shoes. Now, thanks to Nike, the shoe dream comes true. When you press a button, the shoes can tie themselves.
The smart alarm clock—Hello Sense
An alarm clock, called Hello Sense, can improve your sleep. It can control the temperature, light and even air quality in your bedroom to help you have a perfect sleep environment. And it can record your sleep cycles.
Sweet potatoes that could save lives
The lack (缺乏) of vitamin A can cause blindness and many other illnesses for illnesses. In sub-Saharan Africa, plant experts are helping them grow a kind of new sweet potatoes. These potatoes can help them fight against some illnesses.
函数y=ax2(a≠0)的图象与a的符号有关的是( )