经前臂静脉团注增强扫描，主动脉弓的平均循环时间约为多少秒()
A．10±
B．20±
C．30±
D．40±
E．50±
参考答案：A
I don't think it's good to copy others' homework. You should ____________it. [ ]
A. get over
B. get on
C. get up
D. get off
完成句子
①小时候,她回忆说,她父母在一起看起来非常幸福.
As a child,__________________,her parents had seemed very happy together.
②他想不起以前曾经这么累过.
He could not before．
