How long have you been studying at this school?—I have been studying here_____. [ ]
It was not until the entrance exams were in sight that that I had so many books to cover and so many exercises to finish.
Who are you going sightseeing _____? —My parents. [ ]
Bin Laden was killed _____May 2, 2011. [ ]
When _______ your computer ___________? —Yesterday afternoon.