It is first person because the author said, "So then I understood," which shows the author is in the situation.
A means the same thing as the English words under the Chinese definition
B means it usually sleeps for 15 minutes at night
C he goes to bed at 10:15 at night
D means he usually goes to be at 10:15 at night
If it’s not mentioned which tense we should use we can say : Yesterday, he was working all day, he will be working that long today as well.
1. do
2. dabo
3.pug
4.they wont call
5.kept telling you
youre welcome