题目内容

石膏制品具有较好的防火性能，其原因是（）。（1）火灾时CaSO4·2H2O脱水，表面形成水膜；（2）石膏制品孔隙率大（3）石膏硬化时约有1﹪的膨胀率；（4）石膏吸水率大；（5）石膏制品导热率低

A. (1)(2)(3)
B. (1)(3)(5)
C. (1)(2)(5)
D. (1)(4)(5)

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