— No one can answer the question _______ we can complete the task in time, do you know? — Yes, and this is because we don’t know the way _______ the scientist used last time．

 Here we have beef, fish and fruit. Help yourself to ______ you like.

—You can’t imagine ____ fantastic fun web chatting is.  —Really? But it may cause a lot of trouble sometimes. 

The old man has two sons，________is a soldier.

Though he got up early, ______ he missed the train.