Who knows the appliance of black tio2 ? ( black Titanium Dioxide) Please Help Me!!!

what does this sentense mean? in this text, what does it mean? (men of letters) After the 1940s, however , there was a widespread tendency,especially prominent in the existential philosophy of (men of letters) such as Jean-Paul Sarter and Albert Camus, to view a human being as an isolated existent who is cast into an alien universe; to conceive the human world as possessing no inherent truth, value, or meaning; and to present human life.... Is this mean: they wrote letters to each other and in their letters they showed their tendency... is this true?what does exactly mean men of letters?

نظرتان در مورد شعر زیر چیست؟ این یک دو سه روز نوبت عمر گذشت---------چون آب به جویبار و چون باد به دشت
هرگز غم دو روز مرا یاد نگشت----------------روزی که نیامدست و روزی که گذشت
شعر از خیام نیشابوری است، پس از رواج شعرهای خیام در غرب فلسفه ی seize the day یا
carpe diem (enjoy life now,live ffor the moment)شکل گرفت.

نظرتان در باره ی شعر زیر چیست؟ این یک دو سه روز نوبت عمر گذشت---------چون آب به جویبار و چون باد به دشت هرگز غم دو روز مرا یاد نگشت----------------روزی که نیامدست و روزی که گذشت شعر از خیام نیشابوری است، پس از رواج شعرهای خیام در غرب فلسفه ی seize the day یا carpe diem (enjoy life now,live ffor the moment)شکل گرفت.

What are the answers of this question?(How are u?) for example: I`m fine,thanks pretty good,thanks Which one is formal and which one is informal?

What was your last goof??????

Who is your favorite english poet? I like George Herbert...!

What are formal greetings in English? Like: Hi, How r u? How do u do?

What is your favorite color and why?