【OG20-P814-906题】In no other historical sighting did Halley’s Comet cause such a worldwide sensation as did its return in 1910–1911.

【OG20-P810-886题】Although appearing less appetizing than most of their round and red supermarket cousins, heirloom tomatoes, grown from seeds saved during the previous year--they are often green and striped, or have plenty of bumps and bruises—heirlooms are more flavorful and thus in increasing demand.

【OG20-P810-885题】Mauritius was a British colony for almost 200 years, excepting for the domains of administration and teaching, the English language was never really spoken on the island.

If the integer n is greater than 1, is n equal to 2 ? (1) n has exactly two positive factors. (2) The difference of any two distinct positive factors of n is odd.

Just as Edward Jenner used the pustules from milkmaids to inoculate against smallpox, effectively removing the specter of death that had hung over the population, the smallpox vaccine today is derived from a live virus, which immunologists have obtained from the pustules of infected organisms.

【OG20-P286-381题】 If a merchant purchased a sofa from a manufacturer for $400 and then sold it, what was the selling price of the sofa?1. The selling price of the sofa was greater than 140 percent of the purchase price.2. The merchant's gross profit from the purchase and sale of the sofa was 1/3 of the selling price.

Rates for having a manuscript typed at a certain typing service are $5 per page for the first time a page is typed and $3 per page each time a page is revised. If a certain manuscript has 100 pages, of which 40 were revised only once, 10 were revised twice, and the rest required no revisions, what was the total cost of having the manuscript typed?

【OG20-P587-693题】Birds have been said to be descended from certain birdlike dinosaur species with which they share distinctive structural features. The fossil record, however, shows that this cannot be so, since there are bird fossils that are much older than the earliest birdlike dinosaur fossils that have been found.Which of the following is an assumption on which the argument relies?

The cathedrals of the Middle Ages were community centers just as much as they were purelyreligious edifices; and they were structures that represented a city’s commitment to a public realm,the opposite of being a private one.

Every fall Croton's jays migrate south. The jays always join flocks of migrating crookbeaks with which they share the same summer and winter territories. If a jay becomes separated from the crookbeaks it is accompanying, it wanders until it comes across another flock of crookbeaks. Clearly, therefore, Croton's jays lack the navigational ability to find their way south on their own.Which of the following, if true, most strengthens the argument above?