Choose the correct option A, B, C, or D for each gap.

The computer has proved to be very (28) _______ to our lives. In fact it can not only do simple (29) _______ add, subtract, multiply or divide - with lightning speed, but also gather a wide range of information for many purposes. They can (30) _______ hand-printed letters, play chess, compose music, write plays or even design other computers. In business and industry, the computer keeps track of sales trends and production needs, mails dividend checks, and makes out company payrolls. (31) _______ they are taking over some of the tasks that were once accomplished by our brains, computers are not replacing us. Our brain has (32) ______ than 10 billion cells and a computer has only a few hundred thousand parts.

The computer has proved to be very (28) _______ to our lives.