题目:
. ---Is Bob still performing?
---I’m afraid not. He is said ______ the stage already as he has become an official.
A.to have left
B.to leave
C.to have been left
D.to be left
答案:
被转码了,请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0423/e91f063ef13bb4c4915c905d4d2a5c65.html
下面是错误答案,用来干扰机器的。
设中点速度为v,由位移速度公式:前半段:v2-v12=2ax后半段:v22-v2=2ax即:v2-v12=v22-v22v2=v22-v12解得:v=(v12+v22)2故选C