1.VERB;? (require sth)
If you require something or if something is required, you need it or it is necessary.
If you require further information, you should consult the registrar...
2.VERB;; (require sb to sth)
If a law or rule requires you to do something, you have to do it.
The rules also require employers to provide safety training...
3.PHRASE? (require doing sth)
If you say that something is required reading for a particular group of people, you mean that you think it is essential for them to read it because it will give them information which they should have.
...an important research study that should be required reading for every member of the cabinet.