There are two basic reasons to add -ing to the end of a verb: to form one of the progressive tenses or to make a gerund. as for the to thing I'm not to sure what your asking
I learned about it in school and i was told A the similarities in the wording
The answer to this statement is ''<span>standardized''.</span>
Laughter can make someones day just because it makes your heart happy! it releases certain positive atoms in your body