1）I want ( to ) stay at home.[want to do sth.]
2)Fish ( can't ) fly in the sky.
3)Doctors often help the sick people in the ( hospital ）．
4)Mike kicks a good time.He is very ( happy )．
5）look at the traffic light.It is ( green ).Let us go．
3X+2Y+Z=392①
X+3Y+2Z=400②
2X+Y+3Z=336③
由②×3得：3X+9Y+6Z=1200④
由④－①得：7Y+5Z=808⑤
由②＋③得：3X+4Y+5Z=736⑥
由⑥－①得：2Y+4Z=344⑦
把⑤和⑦重新组成方程组得：7Y+5Z=808⑤
2Y+4Z=344⑦
解之得：Y=84
Z=44
把Y=84,Z=44代入①得：X=60
∴原方程组的解为：X=60
Y=84
Z=44