No, it is not correct to say "one an." The correct phrase is "one and a half day" to refer to one full day and half of another day.
No, it is more correct to say, "What day is it today?"
It would be correct to say "I haven't seen him for two days" if they left on Monday and today is Wednesday.
"Have a euphoric day" is the correct expression.
Yes, it is correct to say "in these times" to refer to the current period or era. It is commonly used to discuss the present day or recent events.
The sentence structure is a bit awkward. It would be better to say, "Have a wonderful day ahead" or "I hope you have a wonderful day ahead."
It is correct to day "he divided the cake in half". The alternative is to add a word and say "he divided the cake into halves".
Either one is correct; the meaning is the same.
No, it is more correct to say, "What day is it today?"
Not quite. The word 'day' should be plural: There are thirty-one days.
It would be correct to say "I haven't seen him for two days" if they left on Monday and today is Wednesday.
Sure.
It is correct to say "such an exhausting day", and not 'Such an exhaustive day'.
"Have a euphoric day" is the correct expression.
Is it correct to say no one cares?
No.
It's all right with me :)
yes it's absolutely correct