after leaving his post,he still kept himself( )of the world affairs by reading newspapers1\to inform2\being informed3\informed4\informing

after leaving his post,he still kept himself( )of the world affairs by reading newspapers
1\to inform
2\being informed
3\informed
4\informing

选3
keep oneself done of sth.
使自己了解情况
在他离职之后,他仍然通过看报纸了解世界事务