题目

若函数，则函数的零点是___________. 答案：【答案】0或【解析】先令等于,再根据分段函数分情况求解.解：要求函数的零点,则令,即,又因为：,①当时,,,解得.②当时,,,解得（负值舍去）,所以.综上所以,函数的零点是0或.故答案为：0或朗读下面的对话，并运用后面列出的交际用语把该对话完成，注意其中有两项为多余选项。 　　－Hi, Jeff, can you come to my party on Saturday? 　　－________ 　　－It's at seven o'clock. 　　－________ 　　－Mary, can you come to my party? 　　－________ I have to study for a test. 　　－What about you, Dave? 　　－I'm sorry , too. ________ [　　] ①He's not feeling well. ②I have a piano lesson. ③What time is it? ④Sorry, I can't. ⑤Great, I'd love to. ⑥Sure, I can.