The runners________ several times ________their positions on the starting line, otherwise they will be kicked out

You _____ such a serious mistake if you had followed his advice.

I ________ for Beijing in a few days. Do you know when the earliest plane _________

No person _______ carry a mobile phone into the examination room during the national college Entrance Examinations.

Can we visit Hong Kong this summer holiday— I wonder it is the best time to go there.