Unit 6 How long have you been collecting shells? 单元检测题. 单项选择(20分)( )1. _ has Alison been skating? Two years. A. When B. How often C. How soon D. How long( )2. _ did you get married?Last year.A. When B. How often C. How soon D. How long( )3. _ will you return my bike?In two days. A. When B. How often C. How soon D. How long( )4. _ does Jack play football?Every day.