Difference between about and on

Use about to talk about ordinary, general kinds of communication.
Use on to talk about something more serious or academic.
Compare:

• We had a conversation about money. (A conversation is a kind of ordinary communication. Therefore we use about in this case.)
• She gave a lecture on economics. (A lecture is more academic in nature. Therefore we use on this case.)
• Have you got any books on quantum physics?
• Yesterday, I read an interesting book about dogs.

Difference between above and over

Use above when one thing is not directly over another. Above is also used in measurements of temperature and height.

• There is a nice home above the river.
• The temperature is four degrees above zero.

Use over when one thing covers and / or touches another. Over is also used to talk about ages and speeds.

• Why are you wearing that torn coat over your shirt?
• She must be over forty.

Accept and agree

Before an infinitive, use ‘agree’, not ‘accept’.

• She agreed to come. (NOT She accepted to come.)

You cannot put a that-clause immediately after agree or disagree. For example, you cannot write ‘I agree that smoking should be banned.’ Instead, you have to write ‘I agree with the view / opinion / argument that smoking should be banned’.

More examples are given below.

• I disagree with your opinion that cars should not be allowed in city centres.
• Do you agree with the statement that education should be free for all?