The position with computer is very similar today. A few years ago, computers (1) .....................verylarge and expensive. Business managers and rich people ordered them but they (2) ..................... knowhow to use them. In many countries, however the situation (3) ..................... now completely changed.A lot of people not only own microcomputers but also know how (4) ...................... them.a. Chọn từ đúng cho mỗi chỗ trống1, a. were b, are c, have been d, is2,a, don't b, doesn't c, not d, didn't3,a, has b, have c, had d, are4, a, used to b, to use c, using d, used