using a preposition
can I say "in this year", for example, I wish you all the best in this year?
most grammar books say we don't put prepositions of time before "this", but I've found some examples at BNC, I'm confused (

Question

using a preposition
can I say "in this year", for example, I wish you all the best in this year?
most grammar books say we don't put prepositions of time before "this", but I've found some examples at BNC, I'm confused (

Answer

Right.  It is also correct to say it without the preposition:  "I wish you the best this year".

And I, personally, would opt for using "during this year" instead of "in this year".

Answer

You could say: I wish you all the best this year. Or you could say: I wish you all the best this coming year. But I wouldn't use a preposition here. 
But we do use a preposition for 'at this time' for example.

Answer

It's OK. You may say "in this year" or "during this year". The preposition might emphasize your good wishes.

لا تفوّت فرصة تعلّم لغة جديدة وأنت مرتاح في منزلك. تصفّح مجموعتنا المختارة من مدرّسي اللغات ذوي الخبرة وسجّل في درسك الأول الآن!