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12.6 present obligations must, must not, have to, need must and
must not are
not frequently found in papers, but are often found in specifications or instruction manuals. Forms of
to have to are rare in papers.
Must means that something is an absolute requirement given by a specific authority. Note
to have to is not generally used in such circumstances.
2.
To have to is used to report what an external authority has decided.
3.
Must not means that something has been prohibited by an authority.
4.
Do / does not have to means that something is not mandatory.
The forms hasn’t to ,
haven’t to and
hadn’t to are incorrect.
5.
Need indicates necessity and maybe used to make a recommendation.
6.
Do / does not need mean approximately the same as
do / does not have to . Note although there
is a distinction between do not need and
needn’t it is not relevant for research papers.
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