You tell details about the story and what it was about.
Answer:
It was his usual custom to wash his hands before each meal.
Explanation:
You could say it was his custom
or
You could say he usually washed his hands before meals, using both is redundant.
The adverb clause in this sentence is "so that we can go to the basketball game". It explains the main verb "write" more thoroughly, and gives us an explanation "why" they have to do finish their composition.
Answer:
Main idea especially for outline
