题干

质量相等的两个均匀实心球甲和乙,它们的密度之比ρ:ρ=2:3,则它们的体积之比V:V=____;现将甲、乙两球放入盛有足够多的水的容器中,当它们静止时水对两球的浮力之比为F:F=6:5,则甲球静止时处于____(选填“漂浮”、“悬 浮”或“沉底”),乙球的密度ρ=____kg/m3(已知ρ=1.0×103kg/m3).
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3:2,漂浮,1.2×103

同类题4

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乡村的风

许俊文

       ①风是乡村的魂。它不喜欢老是待在一个地方,到处游荡着,时南时北,忽东忽西的。它走到哪里,哪里就能感觉到乡村的呼吸。

       ②每次从城里回到老家豆村,第一个迎接我的便是风。我们虽然好多年没见面了,但它一点儿也不生分。先是用顽皮的小手,把我服服帖帖的头发拔弄乱,再在我干净的皮鞋和西服上,随意撒些尘土与细碎的草屑。要是春天,风就像一只摇头摆尾的小花狗,当我刚从汽车上走下来,视觉还没来得及舒展开,它就从我的身上嗅出了豆村的气味,亲亲热热地扑过来,伸出温软的小舌头,一下一下舔我的手与脚踝,你赶也赶不走。如果是秋天,风里便有了果实发酵的味道,那幽微的醇意,好像﹣个去镇上打酒的孩子,不小心把酒洒了一路,惹人隐隐地有些陶醉。

       ③因为风的缘故,乡村里许多平常得不能再平常的事物,便有了某种诗意。你瞧,那晚风中的炊烟,怎么看都像是﹣幅悬腕挥就的狂草,云烟乱舞,该虚的地方虚,该实的地方实,那是我们在绢和纸上无法做到的,可谓真正的“天书”了。莲荡也是。一阵风吹过去,一阵风又吹过来,满荡田田的莲叶便乱了。然而,乱是乱了,但却乱出了味道。究竟是什么味道呢?我也说不清。看来这世界上的许多事情,就像这风中的“乱荷”,有一种无法言说的美,一种大美。你可以观,可以赏,但你却没有风的能耐,把好端端的东西破坏了,还居然翻出新意。还有秋风中的那些树木,原本蓊蓊郁郁的,可是经不住风的手轻轻地摇晃,三摇两摇的,就只剩下一副骨骼了。随着黄叶随凤飘逝,树上那些平时看不见的鸟巢,一个一个都露了出来,远远看去,恰似一个个黑色的音符挂在枝柯上……

       ④说到风,我想起了一件事,有一年我从豆村带回一棵小枣树,栽在城里自家的庭院中。栽树之前我是下足了底肥的,可是几年过去了,并没有见它有多少长进。我很纳闷,就问父亲是什么原因。父亲看了看周围的环境,给出两个字:缺风。对,缺风。生长在乡村的树可不是这样的。你千万不要以为风是可有可无的东西,其实它是树和庄稼的神灵。一棵得风的树,就如同一个人得到了机遇,东风来了摇一摇,西风来了晃一晃,每摇晃一次,它的根就往泥土深处扎一扎,晃着晃着,一棵树就在风中长高长粗了。父亲把这种现象叫作“得风水”。记得豆村牛鼻凹里有一棵歪脖子黄栌,据说已经很有些岁数了,可就是长不大。村里有人想把它砍下做犁弓,父亲制止道,这棵树虽然长得不是地方,但只要树头能从这凹里蹿出来,一旦招了风,不愁它不成材。后来那棵黄栌居然有了出头之日,风吹着呼呼地往上蹿,一年一个样,一年又一个样,如今它已经有合抱粗了,成了我们豆村的一个标志。这大概就是神奇的风使然吧。当然神奇的还有我的父亲,尽管岁月的风已经把他的头发吹白了,腰吹弯了,甚至连牙齿也吹脱落了,在风中踽踽而行时,须拄一枝拐杖,然而他能够从飘忽不定的凤里悟出一点“道”,想必也该知足了。

       ⑤乡村里的许多事物,小至一片浮萍,一株草,大到一棵树,﹣座山,都与风息息相关,春风归来遍地绿,它们不得不绿;秋风君临千叶黄,它们不得不黄。在这回黄转绿的变幻之中,永远不老的似乎只有土地,只有风。一拨又﹣拨的风,吹了几千年,几万年,它吹走了许多东西,又吹来了许多东西。庄稼在风中拔节,鸟雀在风中飞翔,驴马在风中打着响鼻,蟋蟀在风中浅唱低吟……

       ⑥倘若没有风,这个世界多么沉寂!

同类题5



    WIRES is short for Wildlife Information and Rescue Service. It is an Australian  organization, established(成立) in 1985 to care for injured and orphaned(失去母兽的) native wildlife. WIRES has a network of hundreds of volunteers who rescue and care for native animals until they are well enough to be released (释放)into the wild. Volunteers look after rescued animals in their own homes and are trained in the special needs of native wild animals.
    When Australians find a native animal in trouble, they often call WIRES for help. WIRES may be asked to look after a possum that has been attacked by a cat, rescue a large lizard that has got its head caught in a drink can, or care for a baby animal who has lost its mother. People call WIRES when they want to move a dangerous snake away from their garden or when they find a seabird that has swallowed(吞下) a fishing line or an owl with a broken wing. Sometimes kangaroos jumped onto the road in front of cars and are run over. Australians are encouraged to check the pouch(育儿袋)of dead kangaroos in case there is a baby in it. WIRES volunteers find themselves caring for many babies orphaned in this way.
Each year, in the summer, parts of Australia suffer from(受苦) huge bush fires. These fires not only destroy human homes and put people in danger, but they also destroy animal habitats(栖息地)and endanger the animals living in the bush. After a big fire, WIRES and other organizations go into the district to pick up surviving animals. They are treated for burns, shock, smoke and other problems and then cared for until new location can be found for them.
    WIRES is also involved in educating people in the importance of caring for wildlife and wildlife habitats. Volunteers visit schools and other public places to talk about native animals. Sometimes they bring a bat or some other interesting animals with them to show to people who may never have seen one up close before.