问题 选择题

如图所示,L1、L2、L3为完全相同的灯泡,电源内阻不计,L为直流电阻可忽略的自感线圈,开关K原来接通.当把开关K断开时,下面说法正确的是(   )

A.L1闪亮一下后熄灭

B.L2闪亮一下后恢复原来的亮度

C.L3变暗一下后恢复原来的亮度

D.L3闪亮一下后恢复原来的亮度

答案

答案:D

题目分析:开关接通时被短路不亮 断开瞬间由于线 圈自感产生一电动势(相当于电源)与原来的电源串联,所以更亮而后恢复原来亮度,故C错误D正确;串联后变得更暗,由不亮到亮不再熄灭,故AB错误.

故选:D

点评:做本类题目要注意:线圈与哪种电器相配,是电容还是电阻,再结合线圈特点分析.

阅读理解

Time was running out, and Mark Dickinson wasn't sure whether he'd get to see his dying 2-year-old grandson one last time. A long line at Los Angeles International Airport's security checkpoint had kept him from getting to his gate on time.

His grandson Caden would be taken off life support in a matter of hours in Denver, Colorado, with or without his grandfather's presence, according to CNN affiliate KABC.

“I was kind of panicking because I was running late, and I really thought I wasn't going to make the flight,” Dickinson told KABC.

That's when a pilot from Southwest Airlines stepped up and held the flight at the gate until Dickinson arrived. The pilot was standing by the air bridge waiting for him when Dickinson arrived in socks, so rushed that he just grabbed his shoes at security and ran through the terminal.

“I told him, ‘Thank you so much. I can't tell you how much I appreciated that.’ And he said, ‘No problem. They can't leave without me anyway,’”Dickinson told KABC.

Authorities say Dickinson's grandson, Caden Rodgers, suffered a head injury after his mother's boyfriend threw him across the room. The boyfriend reportedly told police he was drunk and high on marijuana(大麻) at the time. The child later died and the boyfriend has been charged with first-degree murder, according to the Aurora Sentinel.

Thanks to the pilot, Dickinson made it to Colorado in time to say goodbye to his grandson. Most airlines would punish any staff member who holds up a flight, according to consumer advocate Christopher Elliott, who broke the story of the sympathetic pilot on his blog. However, a Southwest spokeswoman said the pilot's actions were praiseworthy.

“You can't hold a plane for every late customer, but I think we would all agree that these were extenuating(可以原谅的) circumstances and the pilot absolutely made the right decision,” Southwest spokeswoman Marilee McInnis said. “I don't think you could ask for a better example of great service for our customers.”

小题1:According to the passage, which is the correct order of the following events?

a. The pilot held the plane for Dickinson.

b. People read the story of the pilot on the Internet.

c. Caden suffered a head injury.

d. Dickinson was waiting in line at the security checking point.

d. Marilee McInnis praised the pilot's actions.

A.d,c,a,b,e

B.c,a,d,b,e

C.c,d,a,b,e

D.d,a,b,c,e小题2:Which of the following statements is true according to the passage?

A.The security staff prohibited Dickinson from getting to his gate on time.

B.The plane couldn't leave without Dickinson according to the regulations.

C.Dickinson made it to see his grandson one last time.

D.Christopher Elliott holds the view that all the airlines should advocate similar actions.小题3:What can we infer from the passage?

A.The boyfriend of Caden's mother hates him very much.

B.The boyfriend has been accused of first-degree murder.

C.Many pilots enjoy writing blog.

D.Dickinson had to take off his shoes at the security cheekpoint.小题4:In writing this passage, the author mainly tells us a story about ________.

A.an unlucky man from Los Angeles making his flight

B.a poor boy being killed by his mother's boyfriend

C.Southwest Airlines' decision not to punish a pilot who held up the flight

D.a pilot holding the flight for a man going to see his dying grandson

问答题 简答题