A:as soon a
B:unle
C:as far a
D:until
⑴Are you Mike? ____
⑵Good afternoon, Miss Li. ____
⑶This is my brother, Tim. ____
⑷She is my sister, Yang Ling.____
⑸Good evening. ____ A. Hello, Yang Ling.B. No, I'm not.C. Good evening.D. Hello, Tim.E. Good afternoon, class.
某质点的位移随时间的变化规律的关系是x=4t+2t2,x与t的单位分别为m和s,则质点的初速度与加速度分别为( )