Believe it or not, there is always something nice to do on weekends. If you take some time to think about your weekends and plan them carefully, they may become more exciting, refreshing and as a result more rewarding. Throughout weekends, you can join in endless activities. You may attend a weekend course to increase your knowledge, for example, listen to a lecture on ancient Egypt. You may also try various activities, such as short countryside trip, or you may want to go skiing on a cold winter weekend. You may invite your best friend to a picnic, tell each other jokes and enjoy each other's company or you may invite more friends to your weekend party and have one another give a talent show. You can help out in a local library or nursing home and do some voluntary   jobs. You can go to a sports ground or amusement centre to play various ball games and others. You may do weekend shopping alone or with somebody. Whatever you do, I hope you have a good weekend. The passage mainly tells us   _  . A) why to plan weekends well B) how to have a nice weekend C) when to attend weekend activities D) where to have a picnic with friends
B

There are some things humans can go without. We can lose a kidney or a lung, an arm or two and still live perfectly well. But some fish put us to shame. They can _ without stomachs. One such fish is the stout longtom. The group it belongs to carries a more appropriate name: the needlefish. All needlefish lack stomachs. Their ancestors had them, but later they were lost. The stout longtom can reach 1.3 meters in length, and lives near the sea surface. Like all needlefish, it can jump out of the water to escape its enemies. Tropical fishermen are sometimes injured by needlefish. In 1977, a 10-year-old Hawaiian boy was killed when a needlefish jumped through his brain. The longtom eats smaller fish. It teeth are not good at cutting fish into pieces, so it swallows fish whole. Ryan Day from Australia and his colleagues wanted to know how the longtom digests its meaty meals without a stomach, so they ran some chemical tests about the fish. Day's results show that the longtom can consume food without the help of a stomach. It uses a special material called trypsin that can break down proteins without acid -- although the approach is less efficient than using a stomach. Because it's a meat-eating animal, the longtom gets a lot of protein in its food, so it can afford this slightly less efficient system for absorbing it. Two plant-eating fish that Day studies actually had higher levels of trypsin in their body, as their food was low in protein. Day thinks that the longtom and its stomachless relatives might actually have arrived at an energy-saving solution. He says that although the stomach is critical to many kinds of animal, the organ is "a fairly expensive organ to run". This perhaps explains why some animals have got rid of theirs. Ryan Day ran the chemical tests in order to find out how the longtom   _  . A) catches smaller fish in the water B) digests the smaller fish in its body C) can jump so high to escape its enemies D) uses acid to break down the protein
B

Adam Smith was the first person to see the importance of the division of the labor. He gave us an example of the process by which pins were made in England.     One man draws out the wire, another strengthens it, a third cuts it, a fourth points it, and a fifth gives it a head. Just to make the head requires two or three different operations. The work of making pins is divided into about eighteen different operations, which in some factories are all performed by different people, though in others the same man will sometimes perform two or three of them.     Ten men, Smith said, in this way, turned out twelve pounds of pins a day or about 4,800 pins a worker. But if all of them had worked separately and independently without division of labor, they certainly could not have made twenty pins in a day and not even one.     There can be no doubt that division of labor is an efficient way of organizing work.  Fewer people can make more pins. Adam Smith saw this, but he also took it for granted that the division of labor is itself responsible for economic growth and development and it accounts for the difference between expanding economies and those that stand still. In fact, the division of labor adds nothing new, and it only enables people to produce more of what they already have. According to the writer, Adam Smith's mistake was in believing that the division of labor   _  . A) was an efficient way of organizing work B) was an important development in methods of production C) finally led to economic development D) increased the production of existing goods

C