I'm a little tired todayI do not know what is the reason
1) I'm a little tired today
I do not know what is the reason ...

2) I'm little tired the day
I am not aware what is the reason ....

هل الجملة الأولى اصح ام الثانية ؟

Question

I'm a little tired todayI do not know what is the reason
1) I'm a little tired today
I do not know what is the reason ...

2) I'm little tired the day 
I am not aware what is the reason ....

هل الجملة الأولى اصح ام الثانية ؟

Answer

More natural:
1) I'm a little tired today
I don't know why.

Answer

I'm A little tired today.
I do not know what the reason IS.

Answer

I'm a little tired today.

I do not know why.
I do not know the reason.
I do not know the reason why.
I do not know what the reason is.
I do not know what the reason why is. [this doesn't sound too good]

"aware" is better when you are told information from someone else. It is probably due to something you did or didn't do.

Đừng bỏ lỡ cơ hội học ngoại ngữ ngay tại nhà. Hãy xem danh sách các gia sư ngôn ngữ giàu kinh nghiệm của chúng tôi và đăng ký buổi học đầu tiên ngay hôm nay!