T5: Present/Past Participle after "be" and Base Form Verbs after Modals

Present/Past Participle after "be"

1.   She was studying the textbooks all night long. 
2.   The pie was cut into six equal pieces. 
3.   Today the teacher is allowing the students to leave class a few minutes early. 
4.   The class is taught every other semester. 
5.   Tom is bringing some drinks to the party. 
6.   The sick child was taken to see a doctor. 
7.   The children are swimming in the backyard pool. 
8.   The diamond jewelry is always kept in a safe place. 
9.   The teacher is preparing a difficult exam for the students. 
10. Dinner is served from 6:00 to 8:00.
11. The homework was done early.
12. He was reading a newspapper every morning.    
13. Tom is taking a book.
14. A house was built on the side of the road.
15. Kylie is watching the movie in the cinema.


Base Form Verbs after Modals

1.   You should try to respond politely.
2.   Everyone must leave the room immediately. 
3.   I could sit on the beach for hours. 
4.   She will ask you many difficult questions.
5.   You can look at the book, but you cannot borrow it. 
6.   He may lie to you because he is not very truthful. 
7.   He knew that he would forgot the phone number. 
8.   The weatherman said that it might snow tonight.
9.   Perhaps we could buy a new car this year.
10. This course will satisfy the graduation requirement. 
11. I can play the piano.
12. you must be kind to everyone.
13. He can speak Arabic.
14. you must walk on the road crossing.
15. He will arrive at 8 a.m. in Jakarta.   


source:
http://www.toeflskill.com/2011/05/problem-with-present-participle-or.html
https://www.englisch-hilfen.de/en/grammar/participles_form.htm
http://www.toeflskill.com/2011/06/problems-with-modals-skill-18.html
http://www.grammar.cl/english/modal-verbs.htm