补全对话。
A: ________ ;
B: Good afternoon.
A: Excuse me. Are you Miss Read?
B: ____, I am. ________your name ?
A: My name is Helen Green.
B: Can you ____ your name, ____?
A: Yes, ____ ; . H-E-L-E-N, Helen, G-R-E-E-N, Green.
B: Thank you.
A:____ ____ .
一辆汽车在高速公路上行驶,由于遇到紧急情况而刹车,以速度vt=7-3t+251+t (t的单位:s,v的单位:m/s)行驶至停止。在此期间汽车继续行驶的距离(单位:m)是( )