煤矿中的煤尘一般都为（）
A.矽尘
B.非矽尘
C.原生粉尘
D.次生粉尘
参考答案：B
Lady Gags is very popular, and she by many boys and girls at school.
A. loves B. is loving C. is loved
发生煤气爆炸事故后，在爆炸地点（）以内不应有火源。
