A：y1＞y2＞y3
B：y3＞y1＞y2
C：y3＞y2＞y1
D：y2＞y1＞y3
People in North China eat noodles as their main food ___ people in the south eat rice.
电热水器能将____转化成____。
除去下列物质中的杂质所选用的试剂（括号内）正确的是（ ）
