题干

已知菱形ABCD的边长为6,对角线AC与BD相交于点O,OE⊥AB,垂足为点E,AC=4,那么sin∠AOE=____

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同类题2

阅读以下语段,完成21——25题 

平生到过不少有名的风景区,但在我的脑子里的印象最深的还是我家乡门前的小溪。春天,春水涨满,桥的两孔像是一对微笑的眼睛。细雨如烟,桥上不时有人打着雨伞走过。对岸的红棉树开花了,燕子在雨中飞来飞去,一阵一阵的风,吹来了断续的笛声……

面对着巨流滚滚的扬子江,我想起了它的发展的历程。

最先它不过是雪山冰岩下面滴沥的小泉,逐渐才变成苍苔滑石间的细流,然后是深谷里跳跃着喜悦的白色浪花的溪涧。以后它又逐渐发展,一时它是澄澈的清溪萦回在牛群牧草之间,一时它又是沸腾咆哮、素气云浮的瀑布,一时它是波平如镜、静静地映着蓝天白云的湖泊,一时它又是飞流急湍、奔腾在崇山峡谷之间的险滩。不知经历了多少曲折和起伏,最后它才容纳了许多清的和浊的支流而形成了茫若无涯的、浩浩荡荡的大江。

我没有到过龙门壶口,没有看到过雁荡龙湫,却看过黄果树的瀑布和许多偏僻地方的大瀑布。

远离瀑布还好几里。就先听到雷鸣,先看到雾气从林中升起。走前去一看,只见一股洪流直冲而下,在日光映射下,像是悬空的彩练,珠花进发,有如巨龙吐沫;水冲到潭里,激起了沸腾的浪花、晶莹的水泡。大大小小的水珠,随风飘荡,上下浮游,如烟如雾,如雨如尘,湿人衣袖。上有危崖如欲倾坠,下有深潭不可逼视。轰隆的巨响,震耳欲聋,同游旅伴虽想交谈几句,也好像失去了声音。

看了瀑布使人感到有一股雄壮宏伟的气势,奔腾冲激的力量,云蒸霞蔚的氛围,它虽然没有具体说出什么,但它的冲劲的确使人振奋。    

小溪流唱着愉快的歌流走了,它将冲击着涯岸流向大海:静静的群山,则仍留在原来的地方,目送那盈盈的水波远去。

    流水一去是决不回来了,但有时也会化作一两片羽云瞭望故乡。

同类题3

阅读理解

    Climate change has had a number of effects on cities around the world, including rising see levels. And, this has become an especially big problem for coastal cities. City officials must now prepare for higher tides on their coasts. The American city of Miami is one example. Located in South Florida, Miami is home to nearly 3 million people and billions of dollars in land and buildings.

    Miami is one of the cities in America most at risk for rising sea levels. The waterfront is central to Miami's culture and economy. But as the seas rise with climate change .the water will not stay put. Large parts of South Florida are in danger of being under water in the coming years. Across Biscayne Bay, the City of Miami Beach is making improvements - raising streets, adding water pumps and more.

    It is costing the city a lot of money. Local communities will spend 500 million dollars for the improvements. Thankfully, the residents, the folks that are paying the bill for this work, realize that the cost of doing nothing is much greater. A possibility officials are discussing with residents is for city to buy homes in some places where flooding has been a problem. The city would then turn that land into parks of grassland that could hold the water.

    Over time, the city may need to take bigger risks. Miami's future depends largely on how much, and how fast, the oceans rise.

    Caroline Lewis leads the climate activism group, the CLEO Institute. She says cities cannot avoid the need to move inland. But, she says,a well-planned withdrawal (撤退) could include measures to keep people safely in place for as long as possible. And, she says, the world could learn from such a model. In these two Florida cities built on wetlands, there remains a lot of hopefulness.