题干

下列关于透镜的说法中,正确的是

A:凸透镜起会聚作用时成的是实像,起发散作用时成的是虚像

B:生物课上使用的显微镜,其物镜是凸透镜,目镜是凹透镜

C:物体在投影仪中成放大、倒立的实像,此时物距大于像距

D:用望远镜观察月球时,月球在望远镜的物镜中成缩小、倒立的实像

上一题 下一题 0.0难度 选择题 更新时间:2020-03-27 06:43:17

答案(点此获取答案解析)

D

同类题1

阅读下列短文,从下面每小题的A、B、C、D四个选项中选出最佳选项。

    I'll tell you a secret. There's a place that gets me every time: whenever I'm there. I can't help but cry. Where is it? It's thousands of metres high in the sky, in a plane, especially when there's a heart-warming comedy on.

    Why am I admitting (承认) this now? Because I'm not alone. The British singer Ed Sheeran says he gets emotional (情绪激动的) when flying too. Also a survey carried out by Gatwick Airport in London found that 15% of men admit they're more likely (可能的) to cry during films in planes than watching at home. And 41% of men admit they often try to hide their tears in another survey by Virgin Atlantic (a British airline). In all, 55% of air travellers in the Virgin Atlantic study said they get emotional when flying. So, what's going on? A study from the Netherlands has shown that adults cry because of feelings of separation, loneliness or powerlessness. All of these are easily experienced when flying: you're far from family, often alone, and have no control over the flight.

    Another   ▲   is that when you're in a plane in the sky, there's not a lot you can do. So you are able to pay more attention to the movies you watch. Then there's the physical space. In a plane, air pressure and oxygen levels are lower, and this can affect (影响) our brain and emotions. On a flight, you may be leaving loved ones or really wanting to see them again, or you might have had a drink at a time you usually wouldn't, and if you see a scene that reflects your emotional state, without doubt it's easier for you to cry.