【单选题】定义集合A-B={x|x∈A且x?B},若集合A={1,2,3,4},集合B={1,2,-5,-7},则A-B=( )
【单选题】启动Excel 2010应用程序后自动建立的工作簿文件的文件名为()。
【简答题】无限花序中花的开放顺序是由 __________到 __________ ;而有序花限中花的开放顺序是由 __________到 __________ 。
【简答题】Paraphrase the following sentences. (Explain the following sentences in your own words and try to bring out the implied meanings) 1. Were elevated 23 feet (Para. 3) 2. The place has been here since 19...