You use an umbrella when it is raining.
he would not use it when it is raining he would use it when it will stop raining.
no. Well yeah it's okay to use a word twice.
"It's raining cats and dogs" is an idiom.
The most useful object to carry when it is raining outside would be an umbrella.
It has to be raining in the morning.
If you keep the karaoke machine inside, then the rain should not be a problem. But if you put it in the rain, it will be ruined.
You should get out of the rain and take all electronics out of the rain.