若$x^2+m^{2}xy+64y^2$是一个完全平方式，则m的值为（   ）

语法填空，阅读下面材料，在空白处填入适当的内容（不多于3个单词）或括号内单词的正确形式。

    At first, only people ____England spoke English. Later, people from England ____ (voyage)to other parts of the world and ____that, English began to ____ (speak) in many other countrieas. Today, ____people speak English as their____, second or foreign language than ever before. Native English speakers can understand each other ____they don't speak ____same kind of English. All languages change when ____ communicate with one another. So there are British English, American English, Australian English and so on. They all have their own identity. Maybe one day Chinese English____ (become) one of the world Englishes.