阅读理解。
Cars!!! Holidays! Thousands of prizes ! Hurry !
FREE with every packet of SPLASH! Your personal lucky number!
Will be among the 500,000 Winners!
Use SPLASH for the SOFTEST …
QIUCKEST…WHITEST WASH!
DON'T DELAY … BUY A PACKET TODAY!
1. This is __________.
A. an introduction to some products
B. An advertisement for selling goods
C. a direction of a kind of washing machine
D. A notice about a football game
2. If you want to get prize, ________.
A. don't delay joining us in playing
B. You should buy 500,000 packets of splash
C. please buy a packet of splash
D. Please drive a car as quickly as possible
3. Those who bought a packet of splash ________.
A. are sure to win a prize
B. Are sure to be among the 500,000 winners
C. could get 500,000
D. Could get the personal lucky number
4. Splash is _________.
A. a certain kind of material used for washing in high quality
B. something like a machine used to wash clothes
C. the softest, quickest, and whitest car to drive
D. one of thousands of prizes for players to win
5. Which of the following diagrams (图解) shows the correct relation ?
=2mc，C球带正电荷2q，静止在匀强磁场B中，A球不带电，以速度v0进入磁场中与C球正碰，碰撞后C球对平面的压力恰好为零，求碰后A球对平面的压力多?(取向右为正)