Present Tense: use / uses

• She uses English at work.
• You use English every day for business.
• Many people use English to communicate.

Present Continuous Tense: (be) using

• You're using your computer to learn English. 

Past Tense: used

• She used English instead of Portuguese.

Infinitive: to use

• Do you know how to use the word "speak" in a sentence?

Gerund: Using English at work is often an important part of a person's job.