Watch this video
Do these exercises.
For the Presents
https://www.examenglish.com/grammar/B1_present_modals_of_deduction.htm
For the past
http://www.autoenglish.org/modalverbs/pastmodalsdeduction.htm
Watch this video
Do these exercises.
For the Presents
https://www.examenglish.com/grammar/B1_present_modals_of_deduction.htm
For the past
http://www.autoenglish.org/modalverbs/pastmodalsdeduction.htm