脊索瘤起源于_____________，常发生于_________、_________、_________部位。
参考答案：胚胎脊索残余；骶尾部；斜坡；脊柱
Once she has ______nothing can change it, Finally, I had to______.
A．made up his mind ; give up
B．make up her mind ; give out
C．made up her mind ; give in
D．make up his mind ; give off
为提高钢铁材料的弹性极限和屈服强度，同时保证较好的韧性，最好采用（）。
A.低温回火
B.中温回火
C.高温回火
