—What ____ you buy yesterday?
一I bought some ____ and some yoghurt(酸奶).
一Don't eat too ____ hamburgers.
They're junk food(垃圾食品).
将栽培植物与野生亲缘植物进行杂交,可以培育出新的优良品种.其本质是利用( )的原理.
The class teacher came up and put a jacket _____ the boy to prevent him from catching a cold .