Fly

【PLAN】 [I]
AmE a plan that will fly will be successful and useful
　News is that the plan for the new hotel isn't going to fly .

fly a kite
to tell people about an idea, plan etc in order to get their opinion
　In my latest book, I wanted to fly the kite for an unfashionable theory.

go fly a kite
AmE spoken used to tell someone to go away, stop saying something, or stop annoying you

fly off the handle informal
to suddenly get very angry
　Calm down, Terry - there's no need to fly off the handle.

fly the flag
to behave in a way that shows that you are proud of your country, organization etc
time flies also the hours/the days etc fly
used to say that a period of time seems to pass very quickly
　'Is it midnight already?' 'Well, you know what they say - time flies when you're having fun !'
time flies by
　The following weeks flew by, and soon it was time to leave.

【FLAG】 [I and T]
if a flag flies, or if you fly it, it is fixed to the top of a tall pole so that it can be easily seen
　After the invasion, people were forbidden to fly their national flag.
　The flags were flying cheerfully in the breeze.
　The government ordered that all flags should be flown at half mast (=halfway down the pole, in order to express public sadness at someone's death) .