二元函数<img src="https://zk.995w.com/lqwvjeImg/fe/fe0c000a6b1881dcb6716b7f962b0c9c.png"style="width:109px;height:21px;">在( )处是连续的。<img src="https://zk.995w.com/lqwvjeImg/49/4961d6c2bb8f75169a36db60b933f0b6.png"style="width:25px;height:18px;"><img src="https://zk.995w.com/lqwvjeImg/36/3630e6ac74369d154946825b328fb19c.png"style="width:157px;height:21px;"> <img src="https://zk.995w.com/lqwvjeImg/88/886e3067847fbbbdeddad27e1c6e2c32.png"style="width:24px;height:18px;"><img src="https://zk.995w.com/lqwvjeImg/e6/e6780a1b627dc7a237024db1ee9dfe95.png"style="width:112px;height:21px;"><img src="https://zk.995w.com/lqwvjeImg/25/25fa0524dca219647f451ea62fc28138.png"style="width:24px;height:18px;"><img src="https://zk.995w.com/lqwvjeImg/9a/9a52a30846e8067ae5c0ee17c9af9c31.png"style="width:157px;height:21px;"> D. <img src="https://zk.995w.com/lqwvjeImg/88/88a6643d59b6f578d814aaa4d08e0a8a.png"style="width:113px;height:21px;"><br>·<img src="https://zk.995w.com/lqwvjeImg/36/3630e6ac74369d154946825b328fb19c.png" <br>·<img src="https://zk.995w.com/lqwvjeImg/e6/e6780a1b627dc7a237024db1ee9dfe95.png" <br>·<img src="https://zk.995w.com/lqwvjeImg/9a/9a52a30846e8067ae5c0ee17c9af9c31.png" <br>·<img src="https://s3.cn-north-1.amazonaws.com.cn/qingshuxuetang/examination/imgUplod/169742432843608cc6e6f1d844c82ab4976d1f9b6b98eimage116.png"