§14.7. Can, could, may, might, must, should, would
English uses so-called "modal verbs" to change a sentence so that it talks about something only possibly happening. For example, the sentence "Fred goes to school" can be modified to "Fred must go to school", "Fred should go to school" or even "Fred might go to school".
Inform supports the use of modal verbs in text substitutions. For example,
"[Fred] [might go] to school."
would in the present tense come out as "Fred might go to school.", but could alternatively be "Fred might have gone to school." As this example shows, all that's needed is to take a verb we'll call V - this case, "go" - and we can write any of these:
"[can V]" or "[cannot V]" or "[can't V]"
"[could V]" or "[could not V]" or "[couldn't V]"
"[may V]" or "[may not V]" or "[mayn't V]"
"[might V]" or "[might not V]" or "[mightn't V]"
"[must V]" or "[must not V]" or "[mustn't V]"
"[should V]" or "[should not V]" or "[shouldn't V]"
"[would V]" or "[would not V]" or "[wouldn't V]"
That helps us to handle informal usages like this one:
"You can't go that way."
To make this message adaptive, we write:
"[We] [can't go] that way."
which can adapt in surprising ways -- "They won't be able to go that way.", for example.
Note that the verb V has to be one that Inform knows. But that's easy:
To discombobulate is a verb.
and then
"[Fred] [might not discumbobulate] so easily."
could produce "Fred might not have discumbobulated so easily", for example.