耐火材料的主要性质有（）度、荷重软化点、高温抗折强度、抗热震稳定性、气孔率和密度以及抗渣性等。
参考答案：耐火
什么是因果图？它与要因图、石川图、树枝图、鱼刺图是什么关系？
Managing money has long been a headache for students mostly supported by their family, who find it ________ to deal with their finances.
A．challenging
B．rewarding
C．demanding
D．exciting
