197. Never use the infinitive sign to by itself; as:

198. Never use don't for doesn't. The use of don't for doesn't is a very common mistake. Don't is a contraction of do not and doesn't of does not. When you are in doubt as to which to use, think or speak the two words in full and see if the verb agrees with the subject. Do not is used with a plural subject, and does not with a singular subject. For example: He don't believe me. This sentence in full would be, He do not believe me, which is incorrect. He does not (doesn't) believe me is correct. Or, They doesn't believe me. This sentence in full would read, They does not believe me, which is incorrect. They do not (don't) believe me is correct.

199. Do not use has got, or have got for must. For example, do not say, We have got to go. Say, We must go. Not, He has got to do what I say; but, He must do as I say.

200. Do not say had ought. For example: You had ought to know better. Omit the had; it is unnecessary and incorrect. Say, You ought to know better.

201. Do not say says I or thinks I.

These are incorrect. Say instead: