I am wondering why "this need" and not "this needs"
I would be grateful if you could provide me with a report and this need not be lengthy.
NOT A TEACHER
I wish to credit Longman English Grammar (by the late and
beloved L. G. Alexander) for the information that I would like to share.
(1) You know that so-called modal verbs are verbs like
can, will, must, etc. And you know that these modal verbs
never take an "s."
(2) Well, sometimes the verb "to need" is used like a
modal by some speakers in the United States (and many speakers
in the United Kingdom, according to Mr. Michael Swan's book Practical
English Usage). As a modal, it's usually used in the negative.
(3) Look at Mr. Alexander's examples:
(a) I do not need to go.
(b) I need not go.
(c) You needn't/don't have to/haven't got to WORK.
(4) Remember sometimes you may not use the modal "need." You
must use the "regular" verb. Mr. Swan says you must say:
"You don't need to pay for emergency calls in most countries."
[P.S. Here in the United States, one calls 911. It's free.] If
a sentence describes habitual [done regularly] or general
necessity, he says to use the regular verb.
This [report] need not be lengthy.(Remember: modals don't take an "s.")
This [report] does not need to be lengthy. (the regular verb)
Thank you & have a nice day.
'Need' is a marginal modal. It means in nonassertive contexts (negatives, interrogatives) it behaves like a modal auxiliary: no inflection, no '-s'. Otherwise 'need' is conjugated like a lexical verb.