19. the best back-up plan for your
presentation would be

this is what i put and it was correct

it's a way for authors to communicate with reader in this time period. books from the past can teach us about life.

there is a sequence and logical steps to give an answer of a trouble.

1) strategy is necessary to develop an project idea.

2) to study and know the environment where you are going to work ( ecosystem).

3)   the materials resources to built the ideas.

4) to give a priority order in the context that you study. in this case human needs.