There are some health problems that, when ______ in time, can become bigger ones later on.

At the bell, the door opened and _____, dashing towards the dinning hall, all shouting and laughing.

It was on a train _____ I was travlling to Xi’an _____ I made the acquaintance of the old professor from UK.

Another reason _____ he didn’t mention is _____ the poor quality of the buildings worsened the damage.

– You must have learnt the good news of our team winning the football match, _____ you?
-- Yes. I _____ it up when having supper in the canteen.

Tom was late for his train, and he asked one of the conductors ______.

At first, my new surroundings were difficult _________

.Only when your identity has been checked ________.

I lost sight of Wang Ping when we reached _________ looked like a large market.

— Where did you meet your middle school teacher?
— It was in the supermarket ______ I was doing some shopping with my son.