阅读下列材料，回答相关问题：

材料1：2011年3月，两名医生将美国心脏病人刘易斯的整个心脏摘除，然后为他安装一个“人造心脏”．这种“人造心脏”主要是由两个类似涡轮的新型离心泵组成．它工作时能保持身体内血液不停流动，完成血液循环．

材料2：2012年1月，英国研究人员成功培育出用于形成血管壁的平滑肌细胞，利用这些平滑肌细胞和从人体取出的皮肤细胞可以在实验室环境中批量“生产”人造仿生血管．人造仿生血管可用于心脏病、肾病等疾病的血管移植手术．

“远东这两个国家(中国、日本)能将它们同欧洲的联系限制在严格监督下的、仅仅是断断续续的贸易之中。但到19世纪中叶，这一形势发生了突然和剧烈的变化。”材料中提到的两国“剧烈的变化”具体指

下列各组句子中，划线词的解释有误的一项是（    ）

如图所示，小球静止在小车中的光滑斜面A和光滑竖直挡板B之间，原小车向左匀速运动，现在小车改为向左减速运动，那么关于斜面A对小球的弹力F_NA的大小和挡板B对小球的弹力F_NB的大小，以下说法正确的是(  )

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In our city, there is a big zoo. There are a lot of different animals in it. There are some scary(吓人的) tigers and lions. They like eating meat and they eat much meat every day.
There are also two big elephants and a baby(幼崽) one. Children like to ride one of them. The elephants are very kind and friendly. They eat much grass and bananas.
In the zoo, we can see different kinds of bears(熊): brown bears, black bears and white bears. They are all shy and clumsy(笨拙的). They stand on their back legs and lift their front legs to ask for food They like cakes very much.
Do you like pandas? There's only one in the zoo. Her name is Lingling. She is very cute. She likes eating bamboos a lot. She is kind of shy, She's very interesting and lovely.