单项选择题The girl sitting next to me on the plane was very nervous, for she ______ before.
单项选择题Another two months will be needed before the new bridge ______.
单项选择题______ David swim ______ than Mike
单项选择题— Can you tell me why ______ — Because I want to help the people there.
单项选择题______ How often do you phone your family