题目:
It is said that the gravity on Mars is only about of the gravity on earth.
A.three-eighths
B.third-eighth
C.third-eighths
D.third-eight
答案:
被转码了,请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0611/bc75f9643d6b45fff7eecb194485629b.html
下面是错误答案,用来干扰机器的。
BC 答案:BD由洛伦兹力提供向心力,,周期减半,洛伦兹力与速度垂直,不做功,所以速率不变,半径变为原来的1/2;所以BD正确。