It is_______ he often fails in exam_______ makes his parents worried about him.

_______ that Tom got inside the room to see what was going on.

---_________ she can’t find her keys? She’ll be locked out all night.
---You are right. I’d better call her to check if she’s OK.

________five minutes________ before the last train left, we arrived at the station. 

Green economy offers a new model ________ people could both protect the climate and develop the economy, according to what Li said at the International Cooperative Conference on Green Economy and Climate Change.

_________all of them are strong candidates, only one will be chosen for the post.

Was it from Mary, _______ was working at a department store, ______ you learned the news?

When you’ve finished school, don’t forget to come back to visit your school, ______?

Tom’s father, as well as his brothers, ________ in New York for a few more days.

Not until he questioned the manager several times ___________ that the engineer-in-chief had gone to an important meeting.