问题 多项选择题

车辆在道路上行驶时,要求道路及道路两旁提供一定的视距空间以保证行车安全,称为视距限界。限界主要有()等种类。

A.横向视距限界

B.平面弯道视距限界

C.纵向视距限界

D.会车视距限界

E.交叉口视距限界

答案

参考答案:B, C, D

解析:

本题考核的是视距限界。车辆在道路上行驶时,要求道路及道路两旁提供一定的视距空间以保证行车安全,称为视距限界。主要有以下三种。

(1)平面弯道视距限界。车辆在平曲线路段上行驶时,曲线内侧的边坡、建筑物、树木或其他障碍物可能会遮挡驾驶人员的视线,影响行车安全。

(2)纵向视距限界。车辆翻越坡顶时,与对面驶来的车辆之间应保证必要的安全视距,约等于两车的停车视距之和。

(3)交叉口视距限界。为了保证交叉口上的行车安全,需要让驾驶员在进入交叉口前的一段距离内,看清驶来交会的车辆,以便能及时采取措施,避免两车交会时发生碰撞。

掌握车辆视距与视距限界,可能会涉及相关考题。

单项选择题

Dogs are constantly learning from the reaction of human owners, picking up facial cues and anticipating their owner’s behavior, a new research suggests. The findings, published online in the journal Learning and Behavior, show that dogs essentially are always in training, and help explain how many owners unknowingly teach and reward their dog’s bad behavior.

Research conducted at the University of Florida focused on the role of eye contact and facial cues in influencing canine behavior. Earlier studies have suggested that dogs seem to know when they are being watched and even wait to perform forbidden behavior like digging in the garden when they know their owners aren’t looking. In this study, researchers studied how human cues triggered begging behavior among 35 pet dogs, 18 shelter dogs and 8 wolves raised in captivity. First the animals were taught that the human strangers helping with the experiment were reliable sources of tasty treats. The testers stood close together and called to the animal, and both offered rewards of Spam cubes or Beggin’ Strips treats.

After four rewards, the experiment began. Two testers stood against a fence or wall, about 20 feet apart and with food in their pockets. The dog was held about 20 feet away, equidistant from both testers. In one condition, one tester faced the dog while the other turned her back. In another, a tester held a book near her face, while the other tester held the book in front of her face, as if she were reading. In a third condition, one tester held a bucket near the shoulder, while the other put the bucket over her head, blocking her eyes.

Then, both testers called out to the dogs. All the animals—pet dogs, shelter dogs and wolves—ignored the person whose back was turned and sought food from the person who was looking at them. "The question was, are dogs and wolves responsive to a human’s attentional state" said Monique Udell, an assistant professor of psychology at Flagler College, Fla. But when the testers held books, it was only the domestic dogs who avoided the person who appeared to be reading the book. "In a house where they’re used to people reading books, they are sensitive to those types of cues," said Dr. Udell. Interestingly, in the bucket experiment, the animals, for the most part, were equally likely to seek food from the person with the bucket over her head as the person holding the bucket.

The experiment shows that dogs are tuned into whether humans are paying attention. "Dogs don’t have to read our minds. Dogs read our behavior," said Dr. Udell. Pet owners often get frustrated with bad dog behavior without realizing that they themselves have reinforced it, either by giving the dog a treat when they beg, skipping a bath when they protest or letting them sleep on the bed or couch.

The new study found that()

A. dogs never behave badly if their owners give them no cues

B. forbidden behavior is harder to train in canine animals

C. dogs’ behavior can never be shaped by conscious training

D. cues from humans help shape the behavior of canine animals

单项选择题