—Sure, ____. The seat is just for you.
A:never mind
B:don't worry
C:go ahead
吊车以2m/s的速度将重物1×105N匀速向上提起,这时钢索对重物的拉力是____ N;若钢索改为以3m/s的速度使重物匀速下降,此时钢索对重物的拉力大小是____ N,方向____.
⑴May I take your picture?____ A. No, I hurt my arm.
⑵Are you okay?____ B. Yes, he is.
⑶Don't draw or write on the wall.____ C. I'm walking to the hotel.
⑷Is Danny busy?____ D. Sure!
⑸What are you doing?____ E. OK, I'm sorry.
古代希腊罗马文明的最后继承者与保存者是( )