As one approaches some crossroads, one comes to a sign which says that drivers have to stop when they come to the main road ahead. At other crossroads, drivers have to go slow, but they do not actually have to stop (unless, of course, there is something coming along the main road); and at still others, they do not have either to stop or to go slow, because they are themselves on the main road.
Mr. Williams, who was always a very careful driver, was driving home from work one evening when he came to a crossroads. It had a "Slow" sign, so he slowed down when he came to the main road, looked both ways to see that nothing was coming, and then drove across without stopping completely.
At once he heard a police whistle, so he pulled in to the side of the road and stopped. A policeman walked over to him with a notebook and pencil in his hand and said, "You didn’t stop at the crossing."
"But the sign there doesn’t say ’Stop’," answered Mr Williams. "It just says ’Slow’, and I did go slow."
The policeman looked around him, and a look of surprise came over his face. Then he put his notebook and pencil away, scratched his head and said, "Well, I’ll be blowed! I am in the wrong street!/

At a crossroads, you reduce your car’s speed when（）

A:there is s stop sign B:there is a slow sign C:you are on the main road D:you are on the crossroad

Today a pilot is totally dependent on what the air traffic controller on the ground tells him. He can’t see enough to be safe. Flight watch is an instrument intended to help him.
On a screen in front of the pilot, there will be a map of the (21) around the plane. The pilot’s own (22) level or height and his own plane at the center of the (23) will show up. On the map any other planes in the airspace will (24) as spots of light with "tails" showing the direction of their light. The flight watch map is (25) for the other planes are not shown at their true (26) , but at their distances away in flying time. This (27) the problem of fast planes being too far away to be seen (28) likely to make contact in seconds and (29) planes that are close enough to be seen but so slow that there’s no chance of (30) for, say, ten minutes.
The pilot will be able to see on the screen whether another plane’s course conflicts with (31) . The screen will show him the flight number of the other plane, so he can contact air traffic control and ask them about the other plane’s course. Then he can take (32) action if necessary. The screen will show him whether his action puts him (33) from yet another aircraft.
Technically, the (34) will be quite complex. Computers will be necessary on the ground and (35) each aircraft to enable Flight watch to collect data about the plane courses and to calculate the distances between planes. But such small computers are now quite cheap, simple and reliable.

31（）

A:small B:slow C:large D:advanced

"... one or two free admission days at slow time." means

A:business is not bad B:business is bad C:strolling is slow D:time is slow

Influenza (travels) exactly as (fastly) as man. In oxcart days (its) progress was (slow).

A:travels B:fastly C:its D:slow

Today a pilot is totally dependent on what the air traffic controller on the ground tells him. He can’t see enough to be safe. Flight watch is an instrument intended to help him.
On a screen in front of the pilot, there will be a map of the (21) around the plane. The pilot’s own (22) level or height and his own plane at the center of the (23) will show up. On the map any other planes in the airspace will (24) as spots of light with "tails" showing the direction of their light. The flight watch map is (25) for the other planes are not shown at their true (26) , but at their distances away in flying time. This (27) the problem of fast planes being too far away to be seen (28) likely to make contact in seconds and (29) planes that are close enough to be seen but so slow that there’s no chance of (30) for, say, ten minutes.
The pilot will be able to see on the screen whether another plane’s course conflicts with (31) . The screen will show him the flight number of the other plane, so he can contact air traffic control and ask them about the other plane’s course. Then he can take (32) action if necessary. The screen will show him whether his action puts him (33) from yet another aircraft.
Technically, the (34) will be quite complex. Computers will be necessary on the ground and (35) each aircraft to enable Flight watch to collect data about the plane courses and to calculate the distances between planes. But such small computers are now quite cheap, simple and reliable.

30（）

A:small B:slow C:large D:advanced

Influenza (travels) exactly as (fastly) as man. In oxcart days (its) progress was (slow).

A:travels B:fastly C:its D:slow

How sleep helps US consolidate memories is still largely a mystery. A recent study from the University of Liibeck, in Germany, offers one clue-Subjects were given a list of 46 word pairs to memorize, just before sleep. Then when they reached the deepest stages of sleep, electrical currents were sent through electrodes on their" heads to induce very slow brain waves. Such slow waves were induced at random in the brains of one group of subjects, but not another.
The next morning, the slow-wave group had better recall of the words. Other types of memory were no| improved, and inducing the slow waves later in the night did not have the same eftect. Why and how the slow waves improved memory is not yet understood, but they are thought to alter the strengths of chemical connections, or synapses, between specific pairs of nerve cells in the brain. Memories are "stored" in these synapses: changing the strength of the synapses increases the strength of the memories they store.
It’s not just memory that is improved by sleep. Recent studies indicate that sleep riot only helps store facts, it also helps make connections between them. Ullrich Wagner arid colleagues in Germany used a puzzle in which players were given a string of numbers, and required to make a series of seven calculations based on these numbers. The seventh calculation (which depended on the preceding six) was the" answer. "Participants repeatedly played the same game with the same roles, but different sets of numbers.
The researchers structured the game such that the second calculation always gave the same answer as the seventh calculation-the final answer. If players recognized this rule, they could get to the final answer much faster. Sonic of the players played the game in the morning, then did other things for eight hours or so, then played the game again. Others played the game first in the evening, then slept, then played it again alter awakening. The players who slept were almost three times more likely to have the insight that allowed them to spot the rule.
Why is this important Some sleep researchers believe that for every two hours we spend awake, the brain needs an hour of sleep to figure out what all these experiences mean, and that sleep plays a crucial role in constructing the meaning our lives come to hold. Breakdowns in such sleep-dependent processing may contribute to the development of depression, and may explain why some people who experience horrific traumas go on to develop post-traumatic stress disorder.
"Synapses" (Line 4, Paragraph 2) can be explained as

A:specific pairs of nerve cells in the brain. B:memories. C:chemical connections in the brain. D:slow waves in the brain.