It helps the customers to buy anything easily without going to market. (Compound)

Internet is a computer-based networking system. (Interrogative)

= Isn't internet a computer-based networking system?

It is a speedy transmitting system of information. (Complex)

= It is a speedy system that transmits information.

Its functions are not only smooth but also rapid. (Affirmative)

= Its functions are both smooth and rapid.

A man has an internet connection and gets a link soon. (Simple)

= A man having an internet connection gets a link soon.

Many educational institutions are greatly benefited through the use of internet. (Complex)

= It is the use of internet through which many educational institutions are greatly benefited.

A student can visit all the renowned libraries of the world without going there. (Passive)

= All the renowned libraries of the world can be visited by a student without going there.