Unity script error message namespace MonoBehaviour not found

I’ve been trying to write a script for my unity project, but the console gives the following error messages.

The type or namespace name ‘MonoBehaviour’ could not be found (are you missing a using directive or an assembly reference?

The type or namespace name ‘Transform’ could not be found (are you missing a using directive or an assembly reference?

Anyone got a clue?

https://i.stack.imgur.com/Ddy7J.png
https://i.stack.imgur.com/524pb.png

>Solution :

It’s using.UnityEngine; small caps, the u in using is written in lowercase.