The plural form for the singular highway is highways.
The plural of highway is highways.
highways
highways
highways
The plural form of the noun highway is highways.the plural possessive form is highways'.
The possessive form for the plural noun highways is highways'.
The word crises is a plural word; it is the plural form of the word crisis.
There is no plural word for if.
Add an 's' to make it highways.
The plural form for the demonstrative pronoun this is these.
A non-plural word, a word (noun or pronoun) that is not plural is singular, a word for just one.
The plural word of delay is delays.