Questions

A credit card's interest rate is the price you pay for borrowing money. For credit cards, the interest rates are typically stated as a yearly rate. This is called the annual percentage rate (APR). On most cards, you can avoid paying interest on purchases if you pay your balance in full each month by the due date.

Your APR is expressed in terms of a year, but credit card companies use it to calculate charges over your monthly statement period.

A colon is used to connect two sentences when the second sentence expands, illustrates, explains, summarizes, or sharpens the first. Both sentences should be complete, and their content should be very closely related.

Example:

This girl has two favorite hobbies: watching movies and seeing how long she can hold her breathe.

Footsteps. 

Yes, as you walk forward, you will leave the footstep behind you.

The alphabet 'Y' resembles same as the questioning word WHY in sounding.

Hence,  alphabet Y is a question.

Distributed systems work in a network. They can share the network resources,communicate with each other.

On election day, voters for The President are really voting for the electors who can elect President.