问题 问答题 简答题

如图所示的点阵是布喇菲点阵(格子)吗?为什么?如果是,指明它属于哪类布喇菲格子?如果不是,请说明这种复式格子的布喇菲格子属哪类?

答案

参考答案:

“面心+体心”立方不是布喇菲格子。

从“面心+体心”立方体的任一顶角上的格点看,与它最邻近的有12个格点;从面心任一点看来,与它最邻近的也是12个格点;但是从体心那点来看,与它最邻近的有6个格点,所以顶角、面心的格点与体心的格点所处的几何环境不同,即不满足所有格点完全等价的条件,因此不是布喇菲格子,而是复式格子,此复式格子属于简立方布喇菲格子。

阅读理解

It had been a long,hard,wonderful day.The two of us had walked from the sea’s edge through the length of a beautiful valley,climbed a superb mountain,travelled its narrow,rocky ridge(山脊),and now stood on its final peak,tired,happy and looking for the perfect campsite.

The experienced backpacker has a natural feeling for such things,and our eyes were drawn to a small blue circle on the map,like an eye winking at us.We could not see it from where we were,but we followed our judgement and went down steeply until it came into view.

We were right.It was a calm pool,with flat grass beside it.Gently taking our packs off,we made the first of many cups of tea before pulling up our tent.Later that evening,over another cup of tea and after a good meal,we sat outside the tent watching the sunset over a sea dotted with islands,towards one of which a ferry was slowly moving.It is not always so perfect,of course.On another trip,with a different companion,a thoroughly wet day had ended at a lonely farm.Depressed at the thought of camping,we had knocked and asked if we could use a barn(谷仓) as a shelter.

Backpacking could be defined as the art of comfortable,self­sufficient(自给自足的) travel on foot.Everything you need is in the pack on your back,and you become emotionally_as_well_as_physically_attached_to_it.I once left my pack hidden in some rocks while I made a long trip to a peak I particularly wanted to climb.I was away for nearly three hours and ended up running the last stretch in fear that my precious pack would not be there.It was,of course.

The speed at which the backpacker travels makes this the perfect way to see any country.You experience the landscape as a slow unfolding scene,almost in the way it was made;and you find time to stop and talk to people you meet.I’ve learned much local history from simply chatting to people I met while walking through an area.At the end of a trip,whether three days or three weeks,there’s a feeling of achievement,of having got somewhere under your own power.

After years of going out walking just for the day,many people start backpacking simply through wanting to stay out rather than cut short a trip.

小题1:The writer and his companion knew there was a pool because ________.

A.they had been told about it

B.they could see it on the map

C.they had seen it earlier in the day

D.they could see it from the top of the mountain小题2:What does the underlined word “it” in Paragraph 2 refer to?

A.The map.

B.The pool.

C.The mountain.

D.The campsite.小题3:How did the writer and his companion feel at the end of the day?

A.They were too tired to put up their tent.

B.They wished they could have found a farm.

C.They were anxious about the coming weather.

D.They were delighted with the spot they’d found.小题4:What does the writer mean by being “emotionally as well as physically attached to it ” in Paragraph 4?

A.It is more than just a practical aid.

B.He walks better when he is wearing it.

C.It is not a good idea to leave it anywhere.

D.He might die on the mountains without it.

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