巴西产的粉红色托帕石中常见（）包体。
A.指纹状
B.管状
C.板状
D.睡莲叶状
参考答案：B
—How did your parents like your idea?
—They always let me ___what I think is right.[ ]
A. to do
B. do
C. doing
D. does
工件长度与直径之比L/d≥（）时，称为细长轴。
A.10
B.15
C.20
D.25
