用轻质的细线将4N的物体系在标有3V0.5W的小电动机上,当小电动机接在3V的电源上时,10s内将物体提升了1m,关于该过程,下列说法错误的是( )
已知(x﹣y+3)2+2x+y=0,求x+y的值.
I to Canada twice. It's so beautiful.