Because the laws/regulations that are implemented are elastic, which means they aren't constricted and can change or be altered as needed.
Answer: Any Chinese who left the United States had to obtain certifications for reentry, and the Act made Chinese immigrants permanent aliens by excluding them from U.S. citizenship.
Explanation: That is what was in my textbook
Great Britain most notably gained all lands east of the Mississippi River, including French Canada.
Primary source is the firsthand experience and evidence of an event, where the any given information first appeared (initial report). The secondary source uses the first source in order to give its information (for example: document that analyzes primary source documents).
When analyzing historical event a researcher use a secondary source instead of a primary source because he uses the primary source as the imput information (facts, events, dates, names) in order to analyze them, connect them and explain them in his work.