Grammar(Verb Pattern)

http://depts.gallaudet.edu/esl/verbpat1to3.htm
I did this exercise and i have got 16 out of 20
the verbs 'enjoy, finish, quit, stop, keep, discuss and practice' use an 'ing' verb if one comes after them.
Verbs such as 'like, love, hate start, begin, continue' can use either a 'to' verb OR an 'ing' verb.
start +to VERB,(VERB+ing)
quit+VERB+ing
enjoy+VERB+ing
like+toVERB,(VERB+ing)
continue +to Verb+ing
want+to VERB
love+to VERB+ing
plan+to VERB
need+ toVERB

Grammar(Modal Verb)

I did this exercise regarding to MODAL VERB which was difficult,I have got 64%
http://elc.polyu.edu.hk/cill/eap/2004/u6/pg135ex2modals.htm