According to the passage, what do people use a diagnostic machine for?

The handling and delivery of mail has always been a serious business, underpinned by the trust of the public in requiring timeliness, safety, and confidentiality. After early beginnings using horseback and stagecoach, and although cars and trucks later replaced stagecoaches and wagons, the Railway Mail Service still stands as one of America’s most resourceful and exciting postal innovations. This service began in 1832, but grew slowly until the Civil War. Then from 1862, by sorting the mail on board moving trains, the Post Office Department was able to decentralize its operations as railroads began to crisscross the nation on a regular basis, and speed up mail delivery. This service lasted until 1974. During peak decades of service, railway mail clerks handled 93% of all non-local mail and by 1905 the service had over 12,000 employees. Railway Post Office trains used a system of mail cranes to exchange mail at stations without stopping. As a train approached the crane, a clerk prepared the catcher arm which would then snatch the incoming mailbag in the blink of an eye. The clerk then booted out the outgoing mailbag. Experienced clerks were considered the elite of the Postal Service’s employees, and spoke with pride of making the switch at night with nothing but the curves and feel of the track to warn them of an upcoming catch. They also worked under the greatest pressure and their jobs were considered to be exhausting and dangerous. In addition to regular demands of their jobs they could find themselves the victims of train wrecks and robberies. As successful as it was, “mail-on-the-fly” still had its share of glitches. If they hoisted the train’s catcher arm too soon, they risked hitting switch targets, telegraph poles or semaphores, which would rip the catcher arm off the train. Too late, and they would miss an exchange.

Which of the following can be inferred from the first paragraph?

How to protect children Web fans from unsuitable material online while encouraging them to use the Internet has long been discussed in the US. For some parents, the Internet can seem like a jungle, filled with danger for their children. But jungles contain wonders as well as hazard and with good guides, some education, and a few precautions, the wilds of the Internet can be safely navigated. “Kids have to be online. If we tell our kids they can’t be allowed to surf the Internet, we’re cutting them off from their future,” said an expert. Most kids have started to use search engines. Many of them are great for finding tons of interesting Internet sites, and they can also locate places where you might not want your kids to go. There are search engines designed just for kids. A certain software contains only sites that have been selected as safe. The most popular way would be to use what is known as a “content screener”. But this can’t be wholly reliable, and the best thing parents can do is to talk to their kids and let them know what is OK or not OK to see or do on the Internet. Another way is that mum or dad is nearby when the child is surfing the Internet. A few other tips as follows: Don’t put the PC in a child’s room but keep it in an area where mum or dad can keep an eye on things. That also makes the Internet more of a family activity. Ask your child what he or she has been doing and about any friends they make online. Tell your child not to give online strangers personal information, especially like address and phone number. And tell your children never to talk to anyone they meet on line over the phone, send them anything, accept anything from them or agree to meet with them unless you go along.

The word “hazard” in the passage means ................

What will happen when an object is dropped into the water?

What does the author say in paragraph 1 regarding most species in Earth’s history?

According to the passage, what can be learnt about passive students?

Which of the following is true, according to the passage?

The final product of the process of drying liquids that uses the first method will be ______.

Why did George Washington not live in the White House?

The word “inhabitants” in line 2 is closest meaning to: .........

The word "excruciating" in the last paragraph means ________.