心左缘上段的结构是()
A.肺动脉段
B.左心室段
C.主动脉结
D.左心房段
E.上腔静脉
参考答案:C
I'm going to the library ______________ my mother. [ ]
A. with
B. and
C. or
A.I= ,从上向下
B.I= ,从上向下
C.I= ,从下向上
D.I= ,从下向上