问题
选择题
下列所说速度中是瞬时速度的有：
A．百米赛跑中，8s末的速度为12.5m/s
B．百米赛跑中，50 m处的速度为10 m/s
C．汽车在一百米内的速度为8 m/s
D．子弹出枪口的速度为800 m/s
答案
ABD
汽车在一百米内的速度为8 m/s是平均速度。所以答案选ABD。
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下列所说速度中是瞬时速度的有：
A．百米赛跑中，8s末的速度为12.5m/s
B．百米赛跑中，50 m处的速度为10 m/s
C．汽车在一百米内的速度为8 m/s
D．子弹出枪口的速度为800 m/s
ABD
汽车在一百米内的速度为8 m/s是平均速度。所以答案选ABD。
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| Jimmy 1 in the country (农村) and he loves 2 in the river near his house, but his father gets a job in a big city and he moves (搬到) there 3 his family. Their new house has a garden, but the garden is small. Jimmy 4 very happy. "Is there a river 5 ?" He is asking his mother 6 the first morning. His mother is answering, "No, there isn't, but there is a beautiful park near here and there is a pool in it. We 7 there this afternoon." Jimmy is happy now. After  lunch, Jimmy and his mother go to the park. Jimmy wants 8 near the pool, but there is a sign (标牌) in front of it. His mother reads it to him. "Warning (注意), this pool is dangerous (危险), 367 people have fallen into it (已掉入)." "Jimmy looks into the pool 9 and he says," But I can't 10 them." | |||
| ( )1. A. lives ( )2. A. plays ( )3. A. and ( )4. A. isn't ( )5. A. near here ( )6. A. on ( )7. A. is going ( )8. A. to walk ( )9. A. care ( )10. A. look | B. living B. playing B. or B. doesn't B. ne ar to here B. in B. are going B. walk B. careful B. see | C. live C. play C. with C. is C. here near C. at C. go C. walking C. carefully C. look for | D. to live D. playes D. to D. not D. here to near D. for D. goes D. walks D. cares D. look at |