问题
选择题
“Underground” is the only word in the English language _____ begins and ends with the letters “und”.
A．what
B．that
C．who
D．whom
答案
答案：B
题目分析：句意：在英语中“Underground”是唯一一个开头和结尾都用字母组合“und”的单词。此处先行词word有不定代词the only来修饰，故用关系代词that来引导。 故选B。
冠斜折，切角缺损，牙髓暴露，鲜红敏感，不松动。