*teaspoons.
The plural of teaspoonful is teaspoonfuls.
There is no plural form. Do and Do not are verbs
The plural form of him, her, or it is them. (objective pronouns)
The plural form of "is" is "are."
The plural form of "was" is "were."
The plural of teaspoonful is teaspoonfuls.
The plural form for the noun teaspoonful is teaspoonfuls.
The plural of teaspoonful is teaspoonfuls.
Teaspoonsful is not necessarily incorrect, but dictionaries use teaspoonfuls as the plural.
Both "cupful" and the plural "cupfuls" use only one L, a common short form used in measurements (teaspoonful, etc.).
There is no plural form. Do and Do not are verbs
The plural form of him, her, or it is them. (objective pronouns)
Bridges is the plural form of bridge.
The plural form of "was" is "were."
The plural form of "I" is "we."
The plural form of "is" is "are."
The plural form of mouth is mouths. The plural form of month is months. The Mounth is a range of hills in Scotland and does not have a plural form.