已知1999amb3与-11a2bn是同类项,则-mn=______.
由同类项的定义可知m=2,n=3,
所以-mn=-23=-8.
故答案为:-8.
— It is a pity that we have nothing to refer to when we come across new words.
— I quite agree with you. There isn't any dictionary around when we need ______.
A.it
B.that
C.this
D.one
气随伞脱的生理基础是
A.气能生血B.气能摄血C.气能行血D.血能载气E.血能生气