题目

如图，在三棱柱中，，，，，分别是和的中点.求证：（1）平面；（2）平面. 答案：【答案】（1）详见解析；（2）详见解析.【解析】（1）连接，证明，即得平面.（2），，平面.证明：（1）连接，在三棱柱中，且，所以四边形是平行四边形.又因为是的中点，所以也是的中点.在中，和分别是和的中点，所以.又因为平面，平面，所以平面.（2）由（1）知，因为，所以.又因为，，，平面In many countries, unusual names for children are becoming more popular, especially when more and more stars give their children special names. In Britain, you can call a child almost anything you like except dirty words. Some parents choose names which come from popular culture. Because of the film the Lord of the Rings(指环王), six boys were named Gandalf. Names about sport are very common, too. Since 1984, 36 children have been called Arsenal after the football team. Other parents like to make up names, or combine(合并) two names to make a special one. A mother in Britain invented the name Tiaamii for her daughter. She combined the names Thea and Amy (the two grandmothers). In China, there are some rules about names ―- you can't use foreign letters or symbols(符号) in a Chinese name. For example, parents are not allowed to name their baby @. In New Zealand, a name beginning with a number is not allowed. Other countries have stricter rules about calling children. For example, Japan, Denmark, Spain, Germany and Argentina have a list of names. Parents must choose the names in the lists for their children. In Britain, some old-fashioned(过时的) names have become popular again, such as Maisie or Ella for a girl, and Alfie or Noah for a boy. But the most popular names are not the strange ones. The top names are very traditional--Jack and Thomas for boys, or Grace and Jessica f6r girls.根据短文内容，选择正确答案，并将其字母代号填入答题卷相应空格内。(共5小题,每小题2分，满分l0分)【小题1】In Britain, people can't use         words in their children's names.    A．strangeB．popularC．old-fashionedD．dirty【小题2】Thirty-six children were called Arsenal because of a        .        A．movie starB．football starC．football teamD．film【小题3】 According to the passage, which of the following names is NOT allowed?     A．Gandulf in BritainB．Tiaarnii in BritainC．李@in ChinaD．Real in New Zealand【小题4】In          , people must name their children according to the list.  A．JapanB．BritainC．AmericaD．China【小题5】From the last paragraph(段落), we know        today.               A．you can name a girl Alfie in BritainB．strange names are the most popular in BritainC．people don't use old names in BritainD．the most popular names are the traditional names in Britain