There are four parts of the day: morning, afternoon, evening and night.
Morning is the first part of the day. It is the time from sunrise till 12 o'clock a.m. In the morning we are busy. We go to school. When we come to school, we say "Good morning" to one another.
The second part of the day is afternoon. The English afternoon is the time from 12 o'clock a.m. to 6 o'clock p.m. In the afternoon people say "Good afternoon". In the afternoon we come home from school.
Evening is the third part of the day. It is the time from 6 o'clock p.m. till sunset. In the evening we do our homework: we read and write, learn English, history, literature, mathematics, physics and other subjects. When friends come, they say "Good evening".
Night is the fourth part of the day. It is the time from sunset till sunrise. At night we are free. When friends go away, they say "Good night".