题干

把两个同规格的灯泡L串联在电源为3伏的电路中,L上标有“3V”的字样,它的电阻随它两端电压的变化关系如图所示,下列说法中正确的是(  )

A:灯泡L的额定电流是0.2A

B:灯泡L此时的电阻是8Ω

C:灯泡L此时能正常发光

D:灯丝的电阻随电压的增大而减小

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答案(点此获取答案解析)

B

同类题5

根据短文内容,从题中所给的A、B、C、D四个选项中,选择最佳答案。
   Little Tommy was doing very badly in math. His parents had tried everything—tutors (家庭教师), cards, special learning centers—in short, everything they could think of. Finally they took Tommy to a catholic (天主教的) school.
   After the first day, little Tommy came home with a very serious look on his face. He didn’t kiss his mother hello. Instead, he went straight to his room and started studying. Books and papers were spread out all over the room and little Tommy was hard at work. His mother was surprised. She called him down to dinner .And as soon as he finished eating,he went back to his room without a word. In no time he was back hitting the books again. This went on for some time, day after day while the mother tried to understand what was happening.
   Finally, little Tommy brought home his report card. He quietly put it on the table and went up to his room and hit the books. His mom looked at it and to her surprise, little Tommy got an “A” in math. She could no longer hold her curiosity (好奇心). She went to his room and asked, “What made you make such great progress ? Was it the nuns (修女)?”
     Little Tommy looked at her and shook his head, “No. ”
   “Well then,” she asked again. “What was it?”
   Little Tommy looked at her and said, “Well, on the first day of school, when I saw that man nailed (钉) to the plus sign (十字架), I knew they weren’t joking. ”