We are ready to offer help _______ you _______ .
Look at the sign _______! We shouldn't park our car here.
The telephone rang_______ Jenny was practicing the violin.A. until B. before C. while
--- Hi, David. _______do you go to see your grandparents?---About three times a month.A. How longB. How oftenC. How soon
The year of 2013 saw the_______ air pollution in China for 52 years.A. bad B. worse C. worst
--- Do you know if Tom_______ to Lily’s birthday party last Sunday?--- Sorry, I've no idea.A. is invitedB. was invitedC. invited