1． ______ they had worked for along time, everyone looked tired.
A． While B． After
C． Unless D． For
2． He has been a teacher ______ he came to the country.
A． since B． until
C． as D． when
3． He has had to cook by himself ______ his mother went on business to Beijing.
A． during B． since
C． after D．when
4． It is ten years ______ I saw you last time.
A． since B． when
5 He always thinks I'm wrong, ______ I may say.
A． no matter whatever B． whatever
C． what D． that
6． ______ , Mother will wait for him to have dinner together.
A． However late is he
B． However he is late
C． However is he late
D． However late he is