按照火灾、爆炸危险的性质,石油化工原料及产品分为哪7类?
参考答案:
爆炸性物质、氧化剂、可燃气体、自燃性物质、遇水燃烧物质、易燃与可燃液体和易燃与可燃固体。
The children talked so loudly at dinner table that I had to struggle ________.[ ]
A. to be heard
B. to have heard
C. hearing
D. being heard
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