Computers are of great        to the development of science and technology.

We can’t afford such an expensive car. You know, our total _____ adds up to no more than $10,000 a year. 

I wished to make a round-the-world tour by plane but I hadn't enough money to pay for the ___.

 --What kind of ________ makes 3G cellphones so popular with the young? --Video communication, I think.

There are a lot of English words that are not spelt __ they sound.