若单项式3amb2与-abn是同类项，则m2-2n=______．
由同类项的定义可知m=1，n=2，
则m2-2n=-3．
下列可出现柏油样便的疾病是（）。
A.内痔
B.肠结核
C.溃疡性结肠炎
D.直肠癌
E.十二指肠溃疡
Her wish is she could lose weight soon.[ ]
A. which
B. that
C. why
D. /
