最常见的良性骨肿瘤是（）。
A.骨软骨瘤
B.软骨瘤
C.骨瘤
D.成软骨细胞瘤
E.骨巨细胞瘤
参考答案：A
—I'm sorry to keep you waiting.
—Oh, not at all, I _____ here only a few minutes. [ ]
A. have been
B. am
C. was
D. will be
下列（）不是栽植的技术环节。
A.起苗
B.运输
C.定植
D.配植
