A:①②
B:①③
C:②④
D:③④
设NA为阿伏加德罗常数的值,下列说法正确的是( )
(2015•四川达州)—Excuse me, could you please tell me the way to the ? I have had too much water.—Go along the street and you will find one.
若x-1+(y+2)2=0,则(x+y)2015等于( )