题目内容
The missing boys were last seen _____ near the river.
A. playing B. to be playing C. play D. to play
A
解析:
现在分词作主语补足语，表示进行。
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Howling(吼叫) is a behavior commonly observed among a wolf pack(狼群). As pack animals, wolves work together to hunt and rely on howling as an important means of communication among each other. There’re different explanations of a wolf’s howl and it appears that there may be more to discover．
One theory is that wolves howl to bond better together. It’s almost as if howling together helps the pack stay together. Perhaps something similar to people feeling a sense of involvement with each other when singing a song together. But this theory may be wrong, explains Fred H. Harrington, a professor who studies wolf behavior.
Indeed, there have been times when wolves have been seen one moment howling in a chorus(合唱), and the next, quarreling among each other. It appears that usually the lowest-ranking members of the pack may actually be “punished” for joining in the chorus at times. So is howling a way to strengthen a social bond or just a way to reconfirm status (地位) among its members? Why do wolves howl for sure?
What is clear, however, is that howling is often used among pack mates to locate each other. Hunting grounds are distant and it happens that wolves may separate from one another at times. When this happens, howling appears to be an excellent means of gathering.
Howling, interestingly, is a contagious behavior. When one wolf starts to howl, very likely others will follow. This is often seen to occur in the morning, as if wolves were doing some sort of “roll call” where wolves all howl together to report their
【小题1】What is the possible similarity between wolves’ howling together and human’s singing in chorus?
| A．The act of calling each other． |
| B．The sense of accomplishment． |
| C．The act of hunting for something． |
| D．The sense of belonging to a group． |
| A．Wolves separate from each other after howling． |
| B．Wolves tend to protect their hunting grounds． |
| C．Wolves sometimes have quarrels after howling together． |
| D．Wolves of low rank are encouraged to join in the chorus． |
| A．show their ranks | B．find their companions |
| C．report the missing ones | D．express their loneliness |
| A．howling is a signal for hunting |
| B．howling is a way of communication |
| C．howling often occurs in the morning |
| D．howling spreads from one to another |
The vitamins necessary for a healthy body are normally supplied by a good mixed diet, including a variety of fruits and green vegetables. It is only when people try to live on a very restricted diet, say that when trying to lose weight, that it is necessary to make special provisions to supply the missing vitamins.
An example of the dangers of a restricted diet may be seen in the disease known as "beri-beri", which used to make large numbers of Eastern people who lived mainly on rice suffer. In the early years of last century, a Dutch scientist named Eijkman was trying to discover the cause of beri-beri. At first he thought it was transmitted by a germ (病菌) . He was working in a Japanese hospital, where the patients were fed on polished rice which had had the outer coverings removed from the grain, it was thought this would be easier for weak and sick people to digest.
Eijkman thought his germ theory was proved when he noticed the chickens in the hospital yard, which were fed on remains from the patients' plates, were also showing signs of the disease. He then tried to separate the germ, which he thought was causing the disease, but his experiments were interrupted by a hospital official, who ordered that the rice without coverings, even though left over by the patients, was too good for chickens. It should be recooked for the patients, and the chickens should be fed on cheap, rough rice with the outer coverings still on the grain.
Eijkman noticed that the chickens began to recover on the new diet. He began to consider the possibility that eating unmilled rice (糙米) somehow prevented or cured beri-beri--even that a lack of some ingredient (成分) in the coverings may be the cause of the disease. Indeed this was the case. The element needed to prevent beri-beri was shortly afterwards separated from rice coverings and is now known as vitamin B. The milled rice, though more expensive, was in fact causing the disease the hospital was trying to cure. Nowadays, this terrible disease is much less common thanks to our knowledge of vitamins.
【小题1】What does the underlined word restricted mean?
| A．balanced | B．limited | C．diverse | D．complex |
| A．It killed large numbers of people. |
| B．It resulted from lack of vitamins. |
| C．It was transmitted by milled rice. |
| D．It was caused by diseased chickens. |
| A．was vitamin B | B．did not affect the chickens |
| C．did not result in beri-beri | D．was named the Eijkman vitamin |
| A．A Good Mixed Diet | B．The New Discovery of Eijkman |
| C．The Dangers of Beri-beri | D．The Importance of Vitamins |