【单选题】The air in big cities _____very dirty by factories.
【单选题】Do you know the student____________?
【单选题】Turn on the television or open a magazine and you ________ advertisements showing happy families. A. will often see B. often see C. are often seeing D. have often seen
【判断题】.PLD作为一种通用型可编程逻辑器件,而它的逻辑功能又是由用户通过对器件编程来自行设定的。
【判断题】可编程逻辑器件的逻辑功能是用户通过对器件编程进行设定的。
【判断题】在汉字产生之前,人们为了帮助记忆、交流思想、传递信息,采用的最原始的记录方法是图画记事。
【简答题】函数曲线 在定义域内( ). (A)有极值有拐点 (B)有极值无拐点 (C)无极值有拐点 (D)无极值无拐点