Use the indefinite articles a and an before nouns: a before a noun that begins with a consonant sound (a doctor, a horse, a university); an before a noun that begins with a vowel sound (an envelope, an hour, an umbrella). And is a coordinating conjunction: use it to join words, phrases, and clauses.
Examples:
A bank is a place where they lend you an umbrella in fair weather and ask for it back when it begins to rain.Usage Notes:
- People worry about whether the correct article is a or an with historian, historic, and a few other words. Most authorities have supported a over an. The traditional rule is that if the h- is sounded, then a is the proper form. . . . This is not a new "rule." Even the venerated language authority H.W. Fowler, in the England of 1926, advocated a before historic(al) and humble.
(Bryan A. Garner, "a. A. Choice Between a or an," Garner's Modern American Usage, Oxford, 2003) - A minor complication arises with some abbreviations. Do you write, "He received a M.A. degree" or "an M.A. degree"? Do you write, "a N.Y. Central spokesman" or "an N.Y. Central spokesman"? The test is how people say or read such designations. "M.A. registers with most people as alphabetical letters, not as "Master of Arts"; hence, "an M.A. degree" is proper. On the other hand, "N.Y. Central" is instantly translated by the mind into "New York Central"; it would not be read as "En Wye Central." Therefore, a "N.Y. Central spokesman" is proper."
(Theodore M. Bernstein, The Careful Writer: A Modern Guide to English Usage, Simon & Schuster, 1965)
Practice:
(a) Writing is just having ______ sheet of paper, ______ pen, ______ not a shadow of ______ idea what you are going to say.
(b) ______ good coach is ______ understanding tyrant ______ a hard-headed friend.
