计算:
2x+3y-[4x-(3x-y)]。
解:原式=
=
=x+2y
The trees____in the storm have been moved off the road.
[ ]
A. being blown down
B. blown down
C. blowing down
D.to blow down
下列关于肺不张的X线表现,错误的是()
A.邻近肺呈代偿性膨胀
B.纵隔向患侧移位
C.胸廓缩小,肋间隙变窄
D.肺门阴影增大
E.肺叶体积缩小,肺纹理消失