How to solve the last two words in the eight characters? When do you use it?

The last two words in the eight characters represent the time of the world. The specific time is:

23: 00- 1: 00, 1: 00-3: 00,

3: 00 -5: 00 in Yin Shi and 5: 00 -7: 00 in Shi Mao.

7: 00-9: 00, 9: 00- 1 1: 00,

Noon11:00-13: 00, noon 13: 00- 15: 00.

Shenshi 15: 00- 17: 00, Youshi 17: 00- 19: 00.

19: 00-2 1: 00, 2 1: 00-23: 00.

Then according to the specific combination of heaven and earth.