----Where did you put the broom,Tom? -----I _______it behind the door．But now it is gone．

— How long is it _____ you picked up your badminton training? — It was not until my finance became better in last December _____ I started the training.

It is _____ Tom often surfs the Internet playing games ______ makes his parents very angry. 

It was three months later _____ he completed the job with difficulty.

It was the building of the rail network from the west to the east coast ________ brought even larger numbers to California in the 1860s.