Right is right. Right7 Of course. But is left wrong Well, the Romans used to think so. They thought left-handed people were mistakes of nature. Latin, the language of the Romans, had many words that expressed this view. Some words we use today still have this meaning. The Latin word "dexter" means "right". The English word "dexterous" comes from this word. It means "handy" (clever with hands). So, right is handy. But the Latin word for left is "sinister". The English word "sinister" comes from this word. Sinister means "evil" (very bad). Is it fair to call right-handed people handy and left-handed people evil Well, fair or not, many languages have words that express such beliefs. In old English, the word for left means "weak". That isn’t much of an improvement over "evil".
Not very long ago, children were often forced to write with their right hands. Doctors have since found that this can be very harmful. You should use the hand you were born to use.
People who use their left hands are just starting to get better treatment. But why they get all these bad names in the first place One reason may be that there are not as many left-handed people as there are right-handed people. There is one left-handed person for every five right-handed ones. People who are different are often thought to be wrong. But attitudes do seem to be changing. Fair-minded right-handed people are finally starting to give left-handed people a hand.
What does the passage lead us to believe when one writes（）
A. He can only use his right hand.
B. He can only use his left hand.
C. He can use either his left hand or his right hand.
D. He can use both his left hand and his right hand.
C/kg的带正电粒子从P点开始进入匀强磁场中运动，初速度
m/s、方向与y轴正方向成夹角θ=53°并与磁场方向垂直．不计粒子的重力作用．已知sin53°=0.8，cos53°=0.6，求： 
