CBC is a famous air company which has over twenty planes carrying passengers and goods, flying along 12 fixed lines all over the world. Its service is very good but some passengers are still not satisfied with it and that is why in 2003 and 2004 the company received letters of complaints from consumers or passengers who pointed out over a dozen kinds of problems which are divided in groups in the following table. Those about passengers’ things carried by the plane are Baggage problems. Customer service refers to service work with passengers are not satisfied with. Over -sales of seats are about the fact that more seats are sold and as a result the plane is too crowded to be safe. Refund problems appear when passengers fail to receive the money paid back to them because of what they have lost. Fares are problems about the price of tickets.
Consumer Complaints Received By the CBC
| Category（种类） | 2003 | 2004 |
| Flight problems | 20.2% | 22.1% |
| Baggage | 18.3% | 21.8% |
| Customer service | 3.1% | 11.3% |
| Over-sales of seats | 10.5% | 11.8% |
| Refund problems | 10.1% | 8.1% |
| Fares | 6.4% | 6.0% |
| Reservation & Ticketing | 5.8% | 5.6% |
| Tours | 3.3% | 2.3% |
| Smoking | 3.2% | 2.9% |
| Advertising | 1.2% | 1.01% |
| Credit | 1.0% | 0.8% |
| Special passengers | 0.9% | 0.9% |
| Others | 6.0% | 5.3% |
| Total Number of Complaints | 2,988 | 1,792 |
51．About how many complaints about Credit were received by the CBC in 2003?
A．28 B．29 C．30 D．31
52．By about what percent did the total number of complaints decrease from 2003 to 2004?
A．40% B．60% C．75% D．100%
53．If the circle graphs below show total consumer complaints for 2003, which graph shows a dark part that is about Flight problems and Refund problems together?
