经验证明，要使一个国家或地区的生态环境比较优越，其森林覆盖率要达到20%。( )

休克时,5～10分钟快速静滴等渗盐水250ml后，如血压升高而中心静脉压不变则提示( )

A．心功能不全

B．血容量过多

C．容量血管过度收缩

D．血容量不足

E．肾功能不全

There are many customs and traditions connected to yearly celebrations which are part of Britain’s folklore (民俗). Lughnasadh is a celebration at the beginning of August. A custom connected with it is to make corn dolls with corn from the last of the harvest. The doll is saved until the following spring when it is put back into the earth with new seeds. People believe that the doll contains the spirit of the corn and will bring a good harvest. Christmas too is full of ancient customs. The traditions of lighting a fire and decorating the home with an evergreen have their roots in times long before Christianity. The fire is to keep away evil spirits and fill the home with light and the evergreen is valued because it is a sign that life continued during those cold, dark days.

Not all the origins of ancient traditions are remembered, however. The roots of Morris dancing, for example, are not known. This is a dance in which men (and sometimes women ) dressed in white dance together. Some people think the dance may be from pre-Christmas times, and others say it was introduced into Britain in the late 15^th century and that it comes from Moorish dancing. In any case, it is interesting to see that Morris dancing is not a dying tradition. There are Morris dancing groups in places as far away as New Zealand and San Francisco!

Although these customs have been passed down to us from forgotten generations, they themselves have not been forgotten and continue to play a part in our modern lives. Every week groups of individuals regularly meet to sing, play instruments or practice ancient dances and this month people all over Britain shall be preparing their homes for the ancient celebration we now call Christmas, lighting fires and putting up Christian trees, just as their great-great–grandfathers once did.

小题1:Why are corn dolls used to celebrate Lughnasadh? （no more than 14 words）(2分)

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小题2:How do people celebrate Christmas according to the passage?（no more than 10 words）(2分)

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小题3:What idea does the underlined sentence try to support ? （no more than 11words）(3分)

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小题4:What’s the main idea of the passage? ( no more than 9 words)  (3分)

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汽轮机在停机过程中，汽缸内壁产生拉应力，而外壁产生压应力。

跆拳道有多少规定品势？

计算题：本题附图所示的开口容器内盛有油和水。油层高度h₁=0.7m、密度ρ₁=800kg/m³，水层高度h₂=0.6m、密度ρ₂=1000kg/m³。

（1）判断下列两关系是否成立，即

（2）计算水在玻璃管内的高度h。