矿物的透明度是指矿物对可见光的反射能力，它取决于矿物对光的吸收率和厚度。
参考答案：错
There are two apple trees _____ Mike's house. [ ]
A. in the front of
B. in the front at
C. in the front
D. in front of
安全封被抽掉的原因？处理方法？
