例句：
Dust masks are graded according to the protection they offer
防塵口罩根據(jù)它們的防護(hù)效果分等級(jí)。
Milk is sold in grades.
牛奶是分等級(jí)出售的。
Why get upset just because you got one bad grade?
何必因?yàn)橐淮纬煽儾缓镁拖氩婚_呢？
All the materials used were of the highest grade.
使用的材料全是優(yōu)質(zhì)品。
You get an A grade for scores of 75 and over.
75分及75以上的分?jǐn)?shù)就是優(yōu)等。