在绿化工作中,理论上应当采取的方法有()
A.选择一种优良树种栽培
B.阴阳性搭配
C.多树种混合种植
D.草、灌、乔结合
E.以美观大方为标准
参考答案:B, C, D
—Is this your eraser?
—No, it isn't. I think _____.[ ]
A. it her eraser
B. its her eraser
C. it's her eraser
D. it's him eraser
肺动脉瓣关闭不全的常见原因是()
A.风湿热
B.肺动脉瓣狭窄
C.肺动脉高压
D.肺动脉栓塞
E.冠心病