【单选题】晶体在受到应力作用超过其极限状态,从晶格中特定方向裂开程光滑平面的性质称为()。
【简答题】There is an increasing number of college students in U.S. who are suffering from depression and anxiety.
【单选题】There is ______ “s” and ______ “u” in the word “bus”.
【单选题】There is ____ “u” and _____ “s” in ____ word “useful”.