measurements 2 ?

[94BANSHEE]

hi. when we talk about tons or tonnes, i hear people say like this:

"It's a 2 tonne truck"

why not " It's a 2 tonnes truck" ?

thanks

[Alan]

When a noun phrase is used attributively, as here, it generally is not pluralized, irrespective of number. The same applies even when the phrase is further embedded in another attributive phrase, thus we have, e.g. a ten-year-old boy, and not *a ten-years-old boy.