Helen borrowed my book _______, saying that she would return it soon.

The traditional approach __________ with complex problems is to break them down into smaller，more easily managed problems.

The conference has been held to discuss the ________of global warming on people’s lives all over the world.

There existed an obvious ________ between the accounts of the witnesses, so a judgment was not announced in court.

A landing on Mars is within the _____ of current physical theory.