Modal Verbs. SHOULD and SHOULDN'T

Should is a modal verb. It doesn't take letter -s in the third person singular. We use it to give advice and to tell people what we think it's best to do.
For example:
You should study your school subjects every day.
The government should help citizens.
We should take care of the environment.

Read and study the presentation below to get familiar with the structure and uses of this modal verb.