It’s the __________ in the west to open a present when someone gives __________ to you.

The practice of hanging clothes across the street is a common ______ in many parts of the city.

I haven’t started writing my novel yet—I am still waiting for ______.

 I have no _____ that you will succeed, but I wonder whether you have really got everything ready.

It is widely accepted that animals learn to do things because their certain acts lead to _______.