如图所示,有三个支架用于放置蜡烛、凸透镜和光屏,且能在光屏成烛焰的像,则 (1)

题型:问答题

问题:

如图所示,有三个支架用于放置蜡烛、凸透镜和光屏,且能在光屏成烛焰的像,则

(1)在实验中,a支架放光屏,b支架放______;c支架放______,这时光屏上成______、______的实像;此成像特点可应用在______上(填“照相机”,“投影仪”或“放大镜”).

(2)如果在上述实验中把光屏与蜡烛的位置对调,光屏上______成像(选填“能”或“不能”).

考点:凸透镜对光的作用
题型:问答题

脱式计算.

(76+38×30)÷76

14×[752-(152+28)]

360×[1000÷(408+92)]

600×[(135-45)÷90]

9846-87×(360÷60)

508×345÷(1526-1521)

题型:问答题

阅读理解。

     I started my food blog (博客) Chubby Hubby in 2005. At the time, we were preparing a wnter's festival.

The chairman wanted to have popular blogs to publicize it. As most of us had no idea what a blog was then,

he suggested that we start our own blogs, just to get an idea.

     It wasn't until much later that I realized I was the only one to do so. A food blog was a good choice for

me. When I first started the blog, I was surprised to find there were others who shared the same hobby in

good food as I did. I became interested in this community (团体). Over the last four years, it's been pleasant

to watch this hobby tum into something that people do as a duty. If you are thinking of starting one, here are

some suggestions:

     Decide who you're talking to. This will decide how the blog voices.

     Be honest. People like to read blogs because they are highly personal insights (洞悉) into people's lives and

interests. If you tell lies, your readers will lose interests.

     Care about design (设计). For food blogs, photography is important. Basic skills help make your blog better.

1. The writer started his food blog because _____.

A. he had read other people's

B. he took food as his hobby

C. someone asked him to do it

D. the festival was held online

2. How does the writer like writing blogs?

A. He enjoys it so much.

B. He likes it just a little.

C. He thinks it's tiring.

D. He thinks it's his job.

3. What does the second suggestion tell us? 

A. To decide who you're talking to.

B. To make sure you are honest.

C. To care about how to design blogs.

D. To know what basic skills are.

题型:问答题

如图所示,物体甲重30N,被50N的水平压力F压在竖直墙壁上保持静止.物体乙重60N,在40N的水平拉力F作用下,沿水平桌面匀速向右运动.则甲受到的摩擦力f和乙受到的摩擦力f分别是(  )

A.f=30N,f=60N

B.f=30N,f=40N

C.f=50N,f=60N

D.f=50N,f=40N

题型:问答题

下列关于惯性的说法中,正确的是(  )

A.物体仅在静止和匀速运动时才具有惯性

B.歼击机战斗前抛掉副油箱是为了减小惯性、提高灵活性

C.物体的速度越大其惯性越大;物体的速度越小则其惯性越小

D.质量相同的物体在月球上比在地球上的惯性小

题型:问答题

湖南省长沙市一名小学生,发现老师和同学们使用木尺在黑板上画线的时候需要一只手扶住木尺,另一只手画线,很不方便。她开动脑筋,结合课堂上学到的科学知识——磁铁具有磁场的性质,在木尺上增加了三块磁铁,发明了磁性木尺,解决了师生经常遇到的大麻烦。这名小学生在发明过程中,是怎样发挥意识能动作用的?

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