主页
学科
搜索
账户
常见问题
当前学科:汽车电气电路基础
题目:
单选
当发电机转速很高时,即使低速触点打开,励磁电流也不再减小,使电压进一步升高,(),励磁电流为零,使发电机的电压下降。
A . 低速触点闭合
B . 高速触点断开
C . 高速触点闭合
D . 低速触点断开
答案:
<查看本题扣1积分>
查看答案
答案不对?请尝试站内搜索
推荐知识点:
安全阀应该垂直装在汽包的()位置。
生命质量测量中相对稳定的指标是()
开标工作由()主持。
大学实践教学的内容体系,大体包括五大类型的实践教学环节,其中之一是()。
心肌收缩性减弱涉及
在设备的保养中,通常为500—700小时进行一次,需停机8小时,则这种保养为()。
生产的火灾危险性分类中,()最危险。
Questions 11 to 15 are based on the following passage. Scratchy throats, stuffy noses and body aches all spell misery, but being able to tell if the cause is a cold or flu (流感) may make a difference in how long the misery lasts. The American Lung Association (ALA) has issued new guidelines on combating colds and the flu, and one of the keys is being able to quickly tell the two apart. That’s because the prescription drugs available for the flu need to be taken soon after the illness sets in. As for colds, the sooner a person starts taking over-the-counter remedy, the sooner relief will come. The common cold and the flu are both caused by viruses. More than 200 viruses can cause cold symptoms, while the flu is caused by three viruses—flu A, B and C. There is no cure for either illness, but the flu can be prevented by the flu vaccine (疫苗), which is, for most people, the best way to fight the flu, according to the ALA. But if the flu does strike, quick action can help. Although the flu and common cold have many similarities, there are some obvious signs to look for. Cold symptoms such as stuffy nose, runny nose and scratchy throat typically develop gradually, and adults and teens often do not get a fever. On the other hand, fever is one of the characteristic features of the flu for all ages. And in general, flu symptoms including fever and chills, sore throat and body aches come on suddenly and are more severe than cold symptoms. The ALA notes that it may be particularly difficult to tell when infants and preschool age children have the flu. It advises parents to call the doctor if their small children have flu-like symptoms. Both cold and flu symptoms can be eased with over-the-counter medications as well. However, children and teens with a cold or flu should not take aspirin for pain relief because of the risk of Reye syndrome (综合症),a rare but serious condition of the liver and central nervous system. There is, of course, no vaccine for the common cold. But frequent hand washing and avoiding close contact with people who have colds can reduce the likelihood of catching one. According to the author, knowing the cause of the misery will help() We learn from the passage that () According to the passage, to combat the flu effectively, () Which of the following symptoms will distinguish the flu from a cold? () If children have flu-like symptoms, their parents ()
水体污染物的转归是指()
男性,69岁,因呼吸困难、双下肢水肿、少尿2天入院。既往慢性咳嗽、咳痰25年,冬季加重。以下检查结果中对诊断肺源性心脏病最有帮助的是()