THE MATH RULES OF SENTENCE STRUCTURE:
Auxiliary verbs
1.
There are three auxiliary verbs, for the simple, continuous, and perfect
forms. They can only be followed by particular verb forms:
1. DO (do, did, does, etc.) for the simple:
DO + simple forms for questions - Did you do your homework?
negatives - I don’t like mushrooms.
emphatic statements - I DID do my homework! (For example, if a
parent says “Why didn’t you do your homework?”)
2. BE (am, is, are, was, were, etc.) + v.-ing for the continuous:
I was driving when it started to rain.
Mark is swimming at the moment.
+ verb-3 for the passive:
Coca-Cola was invented in 1887.
3. HAVE (have, had, etc.) for the perfect - Have you ever been to Milan?
2. Modals
Modals can only be used with a basic-form verb, either spoken/written or
implied:
Can you swim? No, I can’t. (You don’t have to say “No I can’t swim.” Because
“swim” is clearly implied.) There are nine modals, with this mnemonic:
C, C, S, S, W, W, M, M, M
Can could shall should will would, may might must
These are used to take a verb “outside of time”, in that, when I say “I speak
English” it means usually, “I spoke Chinese yesterday” puts it in the past, while
“I can speak Spanish” gives no indication of when the verb “speak” happens.
And, yeah, there are sort of past forms of some of them, such as the past
of “can” is “could”, and will/would, but usually when we put a modal into a past
construction, we have to use modal+have+verb-3 This is where it turns into a
math-like formula.
3. IF clauses and wish sentences:
You can’t use will or would in an IF clause or a wish sentence.
* The one exception is in a statement of exasperation: I wish
you would just shut up! If you would clean your room for once, I
wouldn’t have to nag you!