Sheep f___ on the grass这个词用什么时态啊?因为sheep是不可数名词这里羊是不可数名词，算是第三人称单数吧 为什么不加s？

Sheep f___ on the grass这个词用什么时态啊?因为sheep是不可数名词这里羊是不可数名词，算是第三人称单数吧 为什么不加s？ sheep f____ on the grass . On the Watch Night,there is a big f___ dinner It was on the f___ desk a moment ago. There are some sheep on the hill 划线部分提问划some sheep there are lots of sheep on the farm划线部分：lots of sheep Can you see a few sheep eating grass on the hill?用a little sheep Which country is on the backs of sheep Which country ison the backs of sheep? there are some 什么(sheep) on the hill.急 There are ____(a/an/some) sheep on the hill Look!There are many _____ (sheep)on the hill There are many sheep on the hill.为什么用many? There are many sheep on the farm的同义句 there is sheep on the hill填什么 riding on the back of sheep是什么意思?急! there are no sheep on the hill 同义句 There aren't some sheep on the farm.(改错)