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.
Bridges is the plural form of bridge.
"Beliefs" does not have a plural form, as it is already plural. Beliefs is the plural form of belief.
There is no plural form for the word, countries. This word itself is a plural.
"Groceries" is the plural form of "grocery."
The plural form of "meter" is "meters."
The plural form for the noun sergeant is sergeants; the plural possessive form is sergeants'.
It has no plural form.
The plural form of rung is rungs.
endocytosis
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.