若方程4xm-n-5ym+n﹦6是二元一次方程，则m﹦______，n﹦______．
根据题意，得
m-n=1m+n=1
解，得m=1，n=0．
—_____ are you?
—I'm fine.[ ]
A. How old
B. What
C. Is
D. How
乙酸酐()
