294. Should and ought sometimes express what would certainly be expected in the case supposed.
- Three weeks {should | ought to} suffice.
- If the train is on time, he {should | ought to} arrive at six.
295. Would in all three persons sometimes indicates habitual action in the past.
- I would gaze at the sea for hours at a time.
- Whenever we asked Edward about his adventures, he would begin to talk of something else.
SPECIAL RULES FOR SHOULD AND WOULD
296. Should is the past tense of shall, and would is the past tense of will. Hence the rules for should and would are similar to those for shall and will ([§§ 233–239]). But there is much variation, especially in subordinate clauses.
I. IN SIMPLE SENTENCES AND INDEPENDENT CLAUSES
297. Except in certain kinds of subordinate clauses, the distinction between should and would is practically the same as that between shall and will.
When the auxiliary verb expresses futurity without any idea of wishing, consenting, or the like, the forms are as follows:—
| SINGULAR | PLURAL |
|---|---|
| 1. I should fall. | 1. We should fall. |
| 2. Thou wouldst fall. | 2. You would fall. |
| 3. He would fall. | 3. They would fall. |