‎设函数<img src="https://static.zxtiku.com/wangke/imgs/topic/c924f1429a5ced00951aca28d7090b87.png"/>在<img src="https://static.zxtiku.com/wangke/imgs/topic/9c4f841e6a06c70e56a19d7a7754124e.png"/>上连续，则<img src="https://static.zxtiku.com/wangke/imgs/topic/613d25b7a396605004d0a5950cfa75ab.png"/>时，<img src="https://static.zxtiku.com/wangke/imgs/topic/8a74e232f49f49cbe299720dc253f86a.png"/>（）.