患者，男性，68岁，<img src="/Image1/e1/e19aad285f17fdcc9814774dcf7847d6.jpg" />缺失。余留牙检查：<img src="/Image1/bc/bcfae0f464d232cb7dae58e878528068.jpg" />近中倾斜10°，松动Ⅰ°～Ⅱ°；<img src="/Image1/63/63b40c7a94c93fd2eb9f5f8e3fc02954.jpg" />近中倾斜30°；<img src="/Image1/f0/f0e825bc3e9421e966a585b98d9cfcd2.jpg" />伸长，<img src="/Image1/d4/d4a1dd247b166117e13633a60d55fc23.jpg" />边缘嵴高低约1.5mm；<img src="/Image1/cf/cfdfc4e72e24fadbb429085da0298b64.jpg" />正中时触及下颌嵴顶黏膜，相应黏膜区见浅白色斑块。如保留<img src="/Image1/bc/bcfae0f464d232cb7dae58e878528068.jpg" />，则（）<br>A:制备近中<img src="/Image1/41/416d70c5ce8bf1e24cd865a81ac5ece8.jpg" />支托凹<br>B:近远中各制备一<img src="/Image1/41/416d70c5ce8bf1e24cd865a81ac5ece8.jpg" />支托凹<br>C:作长冠覆盖基牙<br>D:作短冠覆盖基牙<br>E:冠修复后做精密附着体