下列对有关主题知识的归纳完全正确的一组是 [ ]
A．认识元素：
B．元素与人体健康：
C．实验现象：
D．环保与物质的利用：
答案：D
They suggested the professor ____ just now _____ chairman of the meeting. [ ]
A. referring to; was made
B. referring to; be made
C. referred to; be made
D. referred to; was made
设A是四阶方阵，A*是A的伴随矩阵，其特征值为1，-1，2，4，则下列矩阵中为可逆矩阵的是______．
A．A-E B．2A-E C．A+2E D．A-4E
