Learning to write right

In English we have a few verbs called auxiliary or helping verbs that are used with other verbs — called main verbs — to form tenses, and to express the passive, questions or negative statements. They are few in number but very important, and should be known. It is true that those whose mother tongue is English can usually cope with them correctly through normal usage and without knowing anything special about them; but for those to whom English is a second language, it is vital that they should be understood.