单选题Usually you will be (more likely) to find insects (if) you examine finer twigs (rather than) the (coarse) parts of trees.

单选题Many countries have conservation programs to prevent certain ______ of fish from becoming extinct.

单选题Some criminal slang is so highly developed that pickpockets, for example, can ______ a conversation in front of a victim without the person's realizing that they are discussing.

单选题(The farmer) knows something that the whole (civilized) mankind seems (to have forgotten), namely, (when) the resources of life on our planet are not inexhaustible.

单选题Man: You know what? You should invest the money yourself. Woman: That had crossed my mind. Question: What does the woman mean?

单选题What does the word "concurrent" (Par

单选题Despite years of searching, scientists have detected no signs of life {{U}}beyond {{/U}} our own solar system.

单选题The courses aim to give graduates an up-to-date grasp of their subject and ______ laboratory skirls.

单选题Jennifer Senior suggests in her article that raising a child can bring ______.

单选题Wilmut maintains that cloning animals has tremendous potential for helping people. Cloned Sheep, he says, could be used as living drug factories. Scientists could "engineer" sheep that produce drugs in their milk. And by altering the proteins on the surfaces of animal organs to make them more like human organs, scientists believe they may be able to create a plentiful source of organ donors for people. Why not clone humans as organ donors? Theoretically, Wilmut says, there is no reason his techniques couldn't someday be used to clone people. Think about the possibilities: a whole basketball team of Michael Jordans, a scientific panel of Albert Einsteins, a movie starring and co-starring Brad Pitts. On a more serious note, some experts argue that couples who have difficulty having a baby could make copies of themselves. And parents whose child has a fatal disease like cancer might be able to clone the child, creating a twin who could be a bone-marrow (骨髓) donor. But even Ian Wilmut draws the line at cloning humans. "All of us would find that offensive," he says. Several countries, including Britain, Denmark, Germany and Australia, have made all scientific work on cloning humans illegal. The U.S. has no such law, but President Clinton has set up a panel of scientists and philosophers to study the issue. In the meantime, Clinton has imposed a ban on using federal money to clone humans. Humans are more than the sum of their genes, argues a philosopher at one research institute. Though they look exactly the same, clones are not necessarily exact copies. The younger twin might grow up with different influences—say, unusual friends or special teachers. A cloned Albert Einstein might fail his physics class. A cloned pop star might sing terribly. Say you were cloned. Would your twin live a shorter life because he or she started out with DNA that was already 10, 20 or 30 years old? Scientists aren't sure. And how could you prevent someone from taking a sample of your hair and making a clone of you? Again, no solutions. What do you think? Should scientists be allowed to clone animals? How about humans?

单选题Lyndon B. Johnson (was) the only United States President (who) oath of (office) as (administered) by a woman Judge called Sarah Tilghman Hughes.

单选题Recent studies have identified four major global environmental risks; acid rain, ozone (臭氧) depletion, deforestation and the greenhouse effect.

单选题A: I'm sorry, but he's out to lunch right now. B: ______.

单选题(Thirteen hundred) medical professionals, (all of which) have been trained to treat drug dependency, (attended) the annual convention (sponsored) by a society.A. Thirteen hundredB. all of whichC. attendedD. sponsored

单选题Lack of confidence in his own abilities is the chief defect in Mike's character.

单选题I (saw that) the last update was made in (January of) 2002, so I (wondered that) the webmaster (had abandoned) the site.

单选题The new tenant (in) the apartment was (obviously) both (suspicious) and interested (in) his neighbors.

单选题As is known to all, a vague law is always ______to different interpretations.

单选题Over the centuries man has developed drugs that could cure or ______ illness and suffering.