Another Example of Wrong Usage in English

I was browsing some shoes in a hypermarket when I noticed a paper box with the following label.

The phrase ‘at cheapest prices’ is wrong usage here. It should have been ‘at lowest prices’.

Some of my students make mistakes similar to the above example.

e.g. The price of the shirt that I bought was cheap. (Wrong)

There are two ways to correct the above sentence.

a) The price of the shirt that I bought was low.

b) The shirt that I bought was cheap.

Another adjective that is often wrongly used is ‘fast’.

e.g. The car is traveling at a fast speed.

The above sentence is wrong and can be rectified as follows:

a) The car is travelling at a high speed.

b) The car is traveling very fast.