1. Have you finished … the rule?
explain
to explain
explaining
2. The following week, he forgot (do) … it.
do
to do
doing
3.Would you mind ( post) this letter for me?
post
to post
posting
4.Mary enjoys (listen) to music.
listen
to listen
listening
Другое:
5.My friend says he hates (to speak) in public.
speak
to speak
speaking
6.She promissed (not /be) late.
not be
not to be
not being