锁肛痔好发于哪个年龄段()
A.30岁以上
B.40岁以上
C.50岁以上
D.60岁以上
E.任何年龄
参考答案:B
若m-n=2,则2m2-4mn+2n2-1的值为______.
Is your _____ bike as mine? [ ]
A. same
B. some
C. a same
D. the same