Dollars
It is spelled alveolus, and the plural would be alveoli.
The word is spelled children, just as you spelled it. It is the plural of "child".
The word is spelled thefts, just as you spelled it. Thieves would be the plural noun, or the persons committing the thefts.
Singular: dollar. Plural: dollars.
The correct spelling is dinosaur. The plural form would be spelled as dinosaurs.
The correct spelling is mirror. The plural form would be spelled as mirrors.
The plural form of the noun company is spelled companies.
the correct spelling of a plural is opossum.
Margin is the correct spelling of this word. The plural form would be spelled as margins.
The plural of tie is ties.
The plural is a regular S plural, instruments.
It's spelled cacti. The plural form of cactus is like the plurals for octopus and pegasus (e.g. octopi and pegasi). These particular words are spelled in exactly the same way as their Latin root words would be, so the us is changed to i.