Are these sentences, conversation natural V.V.MMXIX

A: Why don't you sell it?

B: I'm afraid that the price will not be as you expected.

She breezed into the pub last night. Everyone was looking at her.

Look that's Jack. Nik's detested brother.

She has twice been convicted of vandals.

I couldn't study in this athoritarian school so I decided to back out.

That man is a ledge! He has finished 20 hamburgers in 12 seconds.

I was gutted when I failed the GCSE Chemistry.

Do you fancy a few sherbets after school?

The situation was fiasco enough to justify failure.

We missed our flight, and on top of that we had to wait seven hours for the next one.

I was revising off and on for the GCSE.

He's got A in all the GCSEs. He's a legend!

It could vary from anything between £1 to £20 plus an annual fee on top of that.

You have to take the bulls by the horns in order to survive in Africa.

I failed 4 subjects. On top of that, I failed English.

The are surplus amounts of class brains.

We will be going on a bender tonight, after school.