1. Learn about/of and Know about/of
We use either about or of with learn and know when we talk about something that happens to somebody or something, or about a particular event. Of is more formal with these verbs.
Example:
- I have just leant about/of the death of Cr. Brown. (= found out about)
- What little is known about/of the plans suggests they will be unpopular.
2) Know and Know about/of
We use know + noun when we talk about personal experience of people and things. Otherwise, we use know about/of + noun.
Compare:
- My uncle knew Churchill. and
- The whole country knew about/of Churchill’s love of cigars.
3) Learn about and Know about
We use learn about and know about (not ‘of’) when we talk about a particular subject that we study.
Example:
- They began to learn about nutrition when they were at primary school.
- Ten years ago we knew little about black holes.
4) Ask about and Enquire about
We use ask about or enquire (or inquire) about when we talk about getting information about something or someone.
Example: He got angry when they started to ask about / enquire about his private life.
5) Ask after and Enquire after
We use ask after or enquire (or inquire) after to ask for information about a person (but not a thing), particularly concerning their health. Ask/Enquire about is also used.
Example: I’m phoning to ask (or enquire) after/about Mrs. Brown. She’s in Ward 4.
NOTE 1: We use ask for (not ‘enquire for’) to ask someone to give you something or do something.
Example: He finished the drink quickly and asked for another.
NOTE 2: We use enquire into (not ‘ask into’) some organization, event or a person we try to find out facts in order to investigate them.
Example: The body has been set up to enquire into near-accidents reported by airline pilots.
6) Think of and Think about
Think of is preferred when we talk about something that suddenly enters your mind (it occurs to you) and think about when you talk about something that you consider over a longer period.
Example:
- He suddenly thought of Hilary. Perhaps she would help. (rather than …thought about…)
- We have been thinking about Jan and her problems for a while. (rather than …thinking of…)
NOTE 1: We use think about (rather than ‘think of’) when we talk about concentrating on something.
Example: Your job is to think about safety and nothing else.
NOTE 2: We use think of (not ‘think about’) to give opinions and ask about them, to talk about an idea, and to talk about remembering something. We also prefer of in the pattern (be) thinking of + ing to talk about intention.
Example:
- What do you think of my car? I’ve just bought it.
- I don’t think a lot of his work. (= it’s not very good)
- He thinks a lot of his sister. (= likes/respects her)
- He’s always thinking of ways to increase our sales.
- I know it’s here somewhere. I just can’t think of where I’ve put it.
- I’m thinking of selling y motorbike.
