The Medford Public Library is hosting a 10-week U.S. Citizenship Test Prep Class directed by the St. Mark Community Education program of Dorchester. The class will meet from 10 a.m. to noon on Saturdays from September 14 through November 16. You will learn how to prepare for the reading and writing test, as well as answers to 100 questions on the civics portion of the test. Participants will need to hold a green card for 4 years,  9 months or…