The soldiers are very tired because they have been at work here ________ 48 hours．

1. A.
   since
2. B.
   after
3. C.
   until
4. D.
   for

China's long-awaited rules on school bus safety finally came into force on Tuesday, including a list of ways aimed at reducing the risk of accident.
Among the biggest changes is that buses carrying students will be given priority(优先权) in traffic, while companies and drivers will need licenses to offer school transport services.
Officials have spent more than four months making the rules, during which time the country has been shocked by several big crashes because of overcrowded school buses.
The latest accident happened on Monday in Yangchun, Guangdong province, in which three kindergarten pupils were killed and 14 others injured.
Rules and funding
In the new rules, a school bus is considered as a vehicle with more than seven seats that is transporting children receiving the State's nine-year compulsory education (ages 6 to 15) to or from school. This can also be for preschoolers(学龄前儿童) if a parent is unable to take them to or from kindergarten（幼儿园）.
School buses must also operate in routes marked in the map by governments to ensure safety.
Punishment
Companies and bus drivers who fail to meet the rules face the punishment.
Drivers against the rules will be fined 200 yuan ($32) and vehicles will be taken away from its owner if they have been used as an unlicensed school bus.
【小题1】New safety rules for school buses can ________.

Here’s the story about Ming’s life on the waters. Ming has lived all his life on a wide r    (1)  in China. His home is a large house-boat with a roof, one of hundreds that move up and down. In about six years he has not once been on l    (2) , but he is never lonely. He is a strong swimmer. In fact（实际上), he could swim before he could walk . When he wants to play with his f    (3) , he just swims across to their boats or asks them to v    (4)  him.
Ming’s father is a fisherman but he never u    (5)   a line or a net（网）. Great black birds called cormorants（鸬鹚）do the fishing for him. Rings （圈） have been put around the birds’ n    (6)  so that they cannot eat the fish they catch. They have been taught to b    (7)  the fish to people. And then people reward （奖励） them with a fine big fish as soon as their work is f    (8)  . Ming loves watching the cormorants, but better still he likes going s    (9)  with his mother. The shops, of course, are boats very like his o    (10) .

Lake Victoria is the largest lake in Africa. It is also the second largest lake in the world. It is an important lake because it is one of the sources(源头) for the longest river in the world, the Nile River. Lake Victoria provides a source of water, food, and power(电力) for several African countries. Lake Victoria is a big part of African life.
Unfortunately, Lake Victoria has a problem. It is shrinking. There are several power stations at Lake Victoria in Uganda. These are on the Nile River, and besides producing power, they keep the water of the lake at a certain level. For the past forty years, that level has been 11.9 meters. Over the last several years, the water level has dropped by about 2.5 meters. There seem to be several reasons for this drop.
One possible reason is drought(干旱). Drought has been very bad in the area since 2000. Lake Victoria gets all of its water from rain, so the drought means less water in the lake.
However, some environmentalists believe that the real problem is the power plants(工厂) on Lake Victoria. Uganda depends on those power plants for most of its power, and they made the power plants larger in 2000. Many people believe the power plants have been taking too much water off Lake Victoria. As a result, they have been asked to use less water until Lake Victoria goes back to its old level.
Whether the low water level is caused by drought or power plants, the result is the same. This is already a poor area of Africa, where many people live a really hard life. People, animals and plants around Lake Victoria will suffer even more from low water levels on the lake. Many people need Lake Victoria for fishing or growing food. Fish need the water to live, and animals need it for water. Plants around the lake will die without the water, and then more animals and people will suffer. Unless the lake fills soon, many people will suffer and die.
【小题1】Lake Victoria is __________.