厂区干道的路面要求中,有单向行驶标志的主干道宽度不小于______m。
A.3 B.5C.7 D.10
参考答案:A
____ several times, the young scientist still kept on doing his experiments.
A.Having failed
B.Having been failed
C.Failed
D.To fail
脊麻时下面哪一项下降最大()
A.右房压
B.左房压
C.心排血指数
D.平均动脉压
E.肺动脉压力