The threats to the health of astronauts in space are very different from ______ on earth. 

---- Have you bought the newly-produced equipment on display?  ----- Not yet, for I still prefer ______ at my home. 

We have been looking at houses, but haven’t found ________ we like yet.

I would appreciate ____ if you could pick me up at the airport tomorrow morning.

 —Who taught her French?—     ! She learned it by herself.