One is single; A year, one year. 2 and higher numbers are plural; 2 years, 3 years... How about half things? 1 and half year (single) or 1 and half years (plural)? How am I supposed to say? I suppose anything over 2 is plural (2 and half years) but how about things between 1 and 2? In Turkish, we refer to every number as if it is single so there is no being complicated. 1 year, 2 year, 3 year, 4 year...Every number is mentioned as if it is single in Turkish language.
In this case, I would simplify to 18 months. For two and a half years, I would use 30 months. Beyond that, unless the time was critical, I would simply say, more than three years etc. In written form, I would not mix words with numbers. One and a half, is correct. PS, (meaning post script) I an pleased that you are keeping well.
Good point in your post 5. Although remembering some of his past posts--he may have good use for some sheeps!
That's the principle of identity. English actually has two grammars, one vague and one explicit, so we don't have to treat numbers the same way all the time.
If I said one and half year in a single way, you would still understand me without having a doubt, right?
Correct and, in fact, one and a half year can be used in a sentence such as, "A one and a half year long tour is mandatory for all space cadets."
Grammar is a legal issue, and academia frequently bends over and greases their ass for Wall Street, which is why they insist on still contradicting themselves all the time, and teaching that English only has one grammar.
I'm much more fonder of the KISS (Keep It Short, Simple) principle. It's the clarity of the message, order, instuction, not the spelling that is important in communication IMO
I can skim through dozens of pages of technical papers, and point out exactly where they make logic errors and assumptions, merely by the shapes of the paragraphs they write. Grammar is as much about geometry as anything else, and to keep it simple when teaching language, requires metaphoric logic the computers are only now becoming powerful enough to produce. I'm working on the basics myself, but there's no way to tell how far I will get, because it requires 430 poems, or root logics, to describe well.
I want to admit that English grammar is very difficult for me, but I still try to learn it. Thank you for your helpful comments. Actually, it usually seems that it's easy, but when I take exams, I have a completely different feeling. But I will do my best to pass the exams and get the certificate I need for my future job. By the way, can recommend me good books and other sources for learning grammar to me? I've recently found a good resource for learning English, where you can find worksheets that provide good English practice for all grade levels -- https://englishlinx.com. And I will be glad to hear your recommendations.