The noun 'transport' is a non-count (mass) noun. Multiples for the noun transport can be forms of transport, choices of transport, illegal transport, public transport, etc.
The only exception is military transport, the military schedules transports for people and equipment.
Transportation is a mass noun. It has no plural form.
Yes, the word 'truck' is a noun, a singular, common, concrete noun; a word for a vehicle used to transport things; a word for a thing.
The plural form of "do" is "do" and the plural form of "don't" is "don't." These words do not change in the plural form when used in a sentence.
The plural form of him, her, or it is them. (objective pronouns)
Bridges is the plural form of bridge.
The plural form of "I" is "we."
The plural form of "was" is "were."
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.
"Groceries" is the plural form of "grocery."
"Beliefs" does not have a plural form, as it is already plural. Beliefs is the plural form of belief.
The plural form of "meter" is "meters."