【题目】Many adults agree that teenagers shouldn't live alone they have their parents’ permission.
A.ifB.unlessC.in caseD.now that
在线课程【答案】B
【解析】
考查状语从句。句意：许多成年人同意，青少年不应该独自生活，除非他们有父母的允许。A. if如果；B. unless除非；C. in case 万一；D. now that由于。此处为条件状语从句，即“在父母允许的条件下”，表示“除非”应用unless。故选B。