Due to the widespread ________ of this medical technology，more diseases can be discovered and treated at an early stage.

Global warming is a big _______ for all and it’s important to raise awareness about climate change.

  _____ of water makes Death Valley a desert, but it is by no means devoid.

--Mum, I’m going to visit my uncle. What about staying there a week?--A week is too long. Try to be back in a _____ of days.

In a time of social reform, people’s state of mind tends to keep _______ with the rapid changes of society.