教育心理学是介于（）和（）之间的交叉学科。
参考答案：自然科学；社会科学
—Did you tell your headmaster that the teachers and students had a number of ________ their lunch?
—Yes. He said he must solve this problem.
A. complains about
B. complaints of
C. complaints about
D complaints of
元素的产生，到达（）元素时就无法“正常”继续了，必须依靠超新星爆发才能够继续产生。
A、氦
B、碳
C、硅
D、铁
