Infinitive

In English, there are two main forms of the infinitive:[1]

• the full infinitive (to-infinitive) has the word to at the beginning. For example: I want to run
• the bare infinitive does not have the word to. For example: I must go.

After a modal verb you must use an infinitive. For example, I must go, he must go (he must goes is not correct)

To express time relationships, here are 6 types of infinitives:

1. simple infinitive, for example, to write
2. continuous infinitive, for example, to be writing
3. perfect infinitive, for example, to have written
4. perfect continuous infinitive, for example, to have been writing
5. passive infinitive, for example, to be written
6. passive perfect infinitive, for example, to have been written

• In German, the infinitives end with -en, -eln or -ern. There are 2 exceptions - sein (to be) and tun (to do).

• In Esperanto, the infinitives end with -i, for example dormi (to sleep)