A:①②
B:①③
C:②④
D:③④
4100,4200,4300,____、____、____.
They went ____the house and____ (look) at the calendar.
若|m﹣2|+|n+3|=0,求m+n的值.
如图,在直角△ABC中,∠C=90°,BC=1,AC=2,下列判断正确的是( )