Comparing particles and particles of doubt and negation

The particle of doubt -dir shows that the speaker does not know for sure but is supposing: Mehmonlar yo‘lga chiqqandir (The guests have probably set off). In form it is the same as the 3rd person suffix -dir of a nominal predicate (u o‘quvchidir — he is a pupil), that is, they are homonyms; but the particle of doubt takes no stress and gives the meaning of supposition. -dir is written joined to the word: kelgandir, bordir. Particles of negation — hech, sira, na ... na — strengthen the negation in the sentence: Bu kitobni sira o‘qimaganman (I have never read this book at all); Hech charchamadim (I did not get tired at all). In a sentence with hech or sira the predicate is usually negative.