It was playing computer games _____ cost the boy plenty of time _______ he ought to have spent doing his lessons.

－Will you please tell her about the news－Sure, I’ll tell her about it as soon as she back.

It is reported that very little use of these waste materials_______ in the past decades

doctors are fighting against H7N9 in China.

It was not until he came back _____ he knewthe police were looking for him.