要使人造卫星绕地球运行，它发射的时候的速度必须等于或大于____km/s，并且小于____km/s；要使卫星脱离地球引力不再绕地球运行，从而在太阳系中飞行，须使它的发射速度等于或大于____km/s；要使它飞到太阳系以外的地方去，它的发射速度必须等于或大于____km/s．（填速度的具体值）

— Yes. He used to ________ the guitar, but now he is more _______ in playing soccer.

①极不可取，会给自己带来很大的安全隐患

②是不会与父母沟通的极端行为

③可以争取自己的权利，保护自己的自由不受任何限制

④应该引起社会、学校、家庭的关注，加强对青少年心理疏导

用所给词的适当形式填空 
All of us can get lots of presents on____ Day. (child)
Our school is big and beautiful. What about____?(they)
Be quiet! The mother with her twin babies____.(sleep)
You just need to practise____English more. (speak)
A good breakfast helps Amy____fit and health. (keep)
____ there a pair of trousers on the bed? I can't find mine. (be)
I don't know what____(choose) in the clothes shop.
There are some boys____ basketball on the playground. (play)
It takes me 2 hours ____ my homework every day. (do)
It's six o'clock now. Millie and Sandy____(not run) in the playground .