1.retain作“保留,保存,保持”解时是较为正式的用语,含有不失去的意味,指继续“保持”或“保存”某事物。可用于指保留贵重的物品,老人保持活力,记忆中保持一定的事实等。
2.retain是及物动词,接名词或代词作宾语。可用于被动结构。retain还可作“挡住”解。

retain on〔upon,over〕(v.+prep.)
对…保持… keep (sth such as influence) over (sb or sth)
▲retain sth on〔over〕 sth
How does an aging politician retain his hold on the loyalty of the voters?一个年迈的政客是怎样使选民继续支持他的呢?
His business has been taken over by a big corporation, but he still retains some control over it.他的商店被一家大公司接管了,但他仍保留部分控制权。
The bank has taken further steps to retain control over the value of the pound.这家银行已采取进一步措施来保持对英镑购买力的控制。

用作及物动词
▲S+～+n./pron.
China dishes retain heat than metal ones do.瓷盘比金属盘能保温。
She tried to retain her self-control.她力图保持自我克制。
We shall retain our rights.我们将保留我们的权利。
This village still retains its old world character.这个村庄仍然保持着古色古香的特色。
She retains a clear memory of her schooldays.她对学生时代的事仍记忆犹新。
He finds it difficult to retain information.他发现记住信息很困难。
Her memory retained everything she read.她过目不忘。
They built a wall round the shore of the lake to retain the water.他们沿着湖边筑起一道堤来挡水。
◇ 用于be ～ed结构
The tickets for the cinema must be retained well by a careful person.电影票必须让细心人保管好。

retain, keep, preserve, reserve
参见keep条。