a large number of 表示許多的,只能修飾可數(shù)名詞；a lot of等于lots of,即可修飾可數(shù)的,又可修飾不可數(shù)名詞；plenty of也是修飾可數(shù)或不可數(shù)名詞,與a lot of同義但不如其常用；a great many只能修飾可數(shù)名詞,等于a good many.記住這些在使用時(shí)就不會(huì)混淆了.例句：
1、A large number of high-tec products have(has) been made in that factory(那個(gè)工廠生產(chǎn)了許多高科技產(chǎn)品）a number of做主語時(shí),動(dòng)詞可用單數(shù),也可用復(fù)數(shù).
2、Don't hurry.We still have plenty of time.
There are plenty of such persons in our school.可數(shù)和不可數(shù)都可以.
3、He got a lot of(lots of)homework(things)to do after school.可數(shù)和不可數(shù)都可以.
4、They raised a great many(a good many)proposals at the meeting.只能是可數(shù)的.
此外,表示大量,許多的還有a large quantity of,修飾可數(shù)和不可數(shù)名詞,如：
As a result of destroying the forests,a large quantity of desert has coverd the land(毀林導(dǎo)致了大量土地的荒漠化）.On that day she received a large quantity of flowers.