We were cornered in a sort of way already. But these butchers up the cavern had been surprised, they were probably scared, and they had no special weapons, only those little hatchets of theirs. And that way lay escape. Their sturdy little forms--ever so much shorter and thicker than the mooncalf herds--were scattered up the slope in a way that was eloquent of indecision. I had the moral advantage of a mad bull in a street. But for all that, there seemed a tremendous crowd of them. Very probably there was. Those Selenites down the cleft had certainly some infernally long spears. It might be they had other surprises for us.... But, confound it! if we charged up the cave we should let them up behind us, and if we didn't those little brutes up the cave would probably get reinforced. Heaven alone knew what tremendous engines of warfare--guns, bombs, terrestrial torpedoes--this unknown world below our feet, this vaster world of which we had only pricked the outer cuticle, might not presently send up to our destruction. It became clear the only thing to do was to charge! It became clearer as the legs of a number of fresh Selenites appeared running down the cavern towards us.

Question: "Where are the Selenites in relation to the narrator?"

OPTIONS:
- no
- yes

Answer: "Below the cavern"

Response: no

Rough surfaces create more friction than smooth surfaces. Thats why cars have tires. Its also why we use rubber mats in areas that might get wet. In your bathtub, you may even use No-Slip tape. No-slip is another way of saying the items has a lot of friction. In Figure 1.9, the blades of the skates are very smooth. Thats why you cant slide across ice with shoes. The soles of your shoes are much rougher than skates. The rougher surface of shoes causes more friction and slows you down. Heavier objects also have more friction. A heavy object presses down with more force. The surfaces are held together more tightly. This makes the surfaces harder to slide past each other. Did you ever try to push something heavy across the floor? Heavy objects are much harder to push than light objects.

Question: "Why do cars have tires?"

Response: "To make them slippery"
OPTIONS:
- no
- yes

A: no

Problem: Dam Good Luck: From the beginning, Las Vegas was built to serve travelers. The railroad needed a way station, and Las Vegas was the place. Growth continued for ten years, and by 1915 the town had telephones, round-the-clock electricity, and a growing populationmany of whom worked in the railroad repair shop. But such heady progress would soon come to a halt. The growing competition in rail transport resulted in Union Pacific buying the Los AngelesSalt Lake line. Union Pacific then consolidated its operations, eliminating the Las Vegas repair facility. Additionally, Las Vegas had been made a part of Nevada's new Clark County in 1909, a year when the legislature also outlawed gambling. These unfortunate circumstances threatened to relegate Las Vegas to the status of a small desert community that could no longer support its 3000 residents. But the southwest's growing need for water, combined with Las Vegas's fortuitous proximity to the Colorado River, would give Las Vegas a second chance to achieve prosperity. Construction on Hoover Dam (originally Boulder Dam, subsequently renamed for the president who authorized the project) began in 1931 in a canyon 45 miles (72 km) southeast of Las Vegas. Providing an influx of $165 million to the southwestern economy, Hoover Dam played a major role in preventing Las Vegas from drying up, both financially and literally. Not only did it create jobs, but it also created Lake Mead, the massive reservoir that today provides water to all of southern Nevada. More Government Help: The construction of Hoover Dam did not single-handedly save Las Vegas, however. The state legislature helped as well, by legalizing gambling in 1931 and thus solidifying the future of the town, though legislators and residents could never have known this at the time. The hordes of people who attended Hoover Dam's 1935 dedication set the city's now-formidable public relations machine into action. They went to work on what has become one of the lengthiest citywide tourism campaigns ever attempted. It didn't take long for the city to establish itself as a wild-West town with an "anything goes" attitude. Vices outlawed or heavily controlled elsewhere were legal here, available any hour of any day (or night).

Question: "What circumstances threatened to relegate Las Vegas to the status of a small desert community that could no longer support its 3000 residents?"

Answer: "Drought and heat"

OPTIONS:
- no
- yes
Answer: no

When you get sick, your body springs to action. Your body starts to fight the illness. Thats why you want to eat right and get plenty of sleep. You need a strong immune system to fight off illness. Plants dont have an immune system. That does not mean they do not get sick. Plants are affected by disease just like us. Typically, their first line of defense is the death of part of the plant. This prevents the infection from spreading. Many plants also produce special chemicals to fight disease. For example, willow trees produce a chemical to kill the bacteria. The same compound is used in many acne products. You can see a picture of a willow tree in Figure Plants may be smarter than we think. No, they cannot talk to each other. They may be able to send messages, though.

Question: "What kind of organisms can get sick even though they don't have immune systems?"

OPTIONS:
- no
- yes

Answer: "Plankton"

Response:
no