某种爆竹点燃后其上升的高度h（米）和时间t（秒）符合关系式h=v0t-12gt2 发布时间：2017-05-12 22:21 │ 来源：www.tikuol.com 题型：填空题 问题： 某种爆竹点燃后其上升的高度h（米）和时间t（秒）符合关系式h=v0t-12gt2，（0＜t≤2）其中重力加速度g以10米/秒2计算．这种爆竹在地面点燃后，以v0=20米/秒的初速度上升，经过______秒离地15米．
题型：填空题 完形填空。 Hearing is very important to all of us. We can 1 beautiful music, nice songs of birds, the laughter of people or other different kinds of 2 in the world with our ears. 3 we must try to protect our ears. The following will tell you 4 protect ears. Listening to 5 music a lot can be bad for ears, 6 when headphones (耳机) are used. So try not to wear headphones or 7 the volume (音量) when you're wearing headphones. You should give your ears a rest if you like wearing headphones. Before swimming, remember 8 earplugs (耳塞) into your ears or wear a swim hat to stop water 9 into your ears. If you are going to a concert, wear earplugs to protect your ears 10 the terrible music! 11 , special earplugs can be made for you if you go to concerts a lot or if you are a musician yourself. See a doctor if your ears 12 . 13 some medicine if the doctor asks you to do so. 14 the advice above now and you won't be saying "what?" when you are getting 15 . ( )1. A. listen ( )2. A. sounds ( )3. A. Because ( )4. A. what ( )5. A. loud ( )6. A. specially ( )7. A. turn on ( )8. A. put ( )9. A. getting ( )10. A. for ( )11. A. In fact ( )12. A. break ( )13. A. Drink ( )14. A. Listen ( )15. A. young B. hear B. noise B. Although B. how B. aloud B. especially B. turn off B. to put B. to get B. from B. In short B. hurt B. Eat B. Hear B. old C. listening C. voices C. So C. what to C. loudly C. special C. turn down C. putting C. with getting C. with C. In general C. ill C. T ake C. Follow C. sick D. hear of D. barks D. But D. how to D. quiet D. especial D. turn up D. to putting D. from gettingD. at D. In a word D. sick D. Have D. Fetch D. tired 查看答案