Her bag _________door [ ]
A. behind the
B. is behind
C. is behind the
答案：C
如果多项式6xn+2-x2-n+2是关于x的三次三项式，代数式n2-2n+1的值是______．
肠扭转最易发生的部位为
A．胃B．盲肠C．乙状结肠D．十二指肠E．小肠
