题目

---The robotic dog (机器狗)produced by Google has been put to good use in the American army recently. ---It is ? a helpful invention for the soldiers (士兵). That means it is for sure useful to them.A. without doubt B. at least C. hardly ever D. at first 答案：【答案】A【解析】句意：谷歌生产的电子狗最近被在美国军队很好的利用。毫无疑问，它对士兵是一项有帮助的发明，那意味着它对他们确实有用。A. without doubt毫无疑问； B. at least? 至少；? C. hardly ever几乎从不； D. at first开始；根据句意故选A若方程4x2-（k-2）x+1=0的两根相等，则k的值是A.6或-2B.6C.-2D.-6或2