题目

设函数，则函数( )A.是偶函数也是周期函数 B.是偶函数但不是周期函数C.不是偶函数是周期函数 D.既不是偶函数也不是周期函数 答案：【答案】A【解析】首先去绝对值，得到分段函数，判断函数的奇偶性，然后根据的值域，求函数，判断函数的周期性.当时，，所以 ，当时，，所以 ，所以 ，函数满足 ，所以函数是偶函数，那么，所以函数是偶函数，时，，所以，，所以函数的值域是，所以，所以是常函数，所以是周期函数，综上可 读写任务 阅读下面的短文，然后按照要求写一篇150词左右的英语短文。 　　The dodo(渡渡鸟)was a kind of pigeon which only lived on the little island of Mauritius in the Indian Ocean．There were no dangerous animals on Mauritius, so the dodo had stopped being able to fly．It simply walked around the forest for food and lived a safe and easy life． 　　This all changed in the 16th century when Portuguese(葡萄牙的)sailors first arrived on the island．The birds were so trusting and slow that the sailors called them “dodo”, which means “a stupid person” in Portuguese．Thousands were killed and eaten, and soon the dodo became an important source of food for all passing ships．Very quickly, the number of dodos started to fall． 　　By 1681, only(200 years after people first set foot on Mauritius, the last dodo had died．The greedy and selfishness of people had destroyed their peaceful lifestyle．The bird which was given the name “stupid”, is now a symbol for the stupidity of human beings． [写作内容] 1．概括短文的内容要点，该部分的词数大约30。 2．就“是否应该保护野生动物”发表你的看法，明确表明反对屠杀野生动物。至少包括以下的内容要点，该部分的词数大约120： (1)介绍野生动物被大肆捕杀现象并分析原因。 (2)提出你的建议。 [写作要求] 你可以使用实例或其他论述方法支持你的观点，也可以参照阅读材料的内容，但不要抄袭阅读材料中的句子。