南矿生产设备夏季换季保养日期为（）
A.三月中旬
B.四月中旬
C.六月中旬
参考答案：B
购买一些彩色纸，单价0.4元/张，总价y元随购买张数x的变化而变化，那y与x的函数关系式为______（不必注明自变量的取值范围）．
Although about ______ of the earth is covered with water, only a very small amount of it is drinkable. [ ]
A. seven-tenth
B. seven tenths
C. seven-tenths
D. seven-tens
