An author wants to add in a second topic into a sentence. She should use?

How does gatsby smile at nick? why is this important?

How has victor changed by the end of frankenstein

Read the paragraph. in fact, teenagers contribute a great deal to their community. this is another reason why they must be taken into account when public policy is debated. over eighty percent of teens spend time volunteering at their schools and other organizations. this is an example of statistical analysis layering point of view outlining