粗集料的强度常用（）指标表示。
A.石料压碎值
B.坚固性
C.软石含量
D.洛杉机磨耗损失
参考答案：A, D
It's not necessary for parents to make their kids _______ the things they don't like.[ ]
A. to do
B. do
C. are doing
简述税收公平原则的具体含义。
