What I have learnt last week

I have learnt:
-Modal verbs
Example:
Should I exercise more or eat less?
The verb 'should' is a modal verb. Could, can, would, may is also modal verbs.
-Active and Passive verbs
Example:
Doris wrote that composition. (Active)
That composition was written by Doris. (Passive)
-Receive and doer
Example:
Sandra bought these new shoes.
In this sentence, 'Sandra' is the doer and 'these new shoes' is the receive.
-In passive voice sentence, there is no doer, the active object become passive subject and active verb become be+ past participle.