Do not use as for that. Not I do not know as this is so, but I do not know that this is so.
Do not use without for unless. We cannot go unless (not without) he comes.
Do not use but what for but that or that. I do not doubt that (or but that) he will come, not but what he will come; They did not know but that (not but what) they might accept it.
Do not use while for although, as, while it is probable. While refers to time.
VERBS
The verb should agree with its subject in person and number. It ought not to be necessary to give this obvious rule, but hardly a day passes without violation of it in almost every paper. Its violation is especially common in the inverted sentence, introduced with there. There is likely to be some changes; There is, at the present writing, some hopes of peace; There seems to be, in view of all the conditions, many objections to this plan, are examples of the faulty usage.
The to should not be separated from the infinitive by word or phrase. The modifier should precede the to or follow the verb. Do not say to promptly act, but to act promptly or promptly to act. Such use as in the example just given is bad enough, but it is not so offensive as the intrusion of time adverbs and negatives as, for example, He decided to now go, or He expected to not only go but to stay, or He preferred to not stay.
Do not end a sentence with the to of an omitted infinitive; as: He could not speak but tried to; but He refused to go but he ought to go, or He ought to go but he refuses.
Subordinate infinitives and participles take their time from the verb in the principal clause. They should therefore be the simple so-called present forms. Do not say: I intended to have gone, or I intended having gone, but I intended to go, I intended going; not He had expected to have been present, but He had expected to be present; not He would have liked to have seen you; but He would have liked to see you; not I was desirous to have gone, but I was desirous to go.