问题
选择题
There is __________ "u" and __________ "r" in the word "umbrella".[ ]
A. a, a
B. a, an
C. an, a
D. an, an
答案
答案：B
搜题请搜索小程序“爱下问搜题”
There is __________ "u" and __________ "r" in the word "umbrella".[ ]
A. a, a
B. a, an
C. an, a
D. an, an
答案：B
缺失，余牙正常，可摘局部义齿修复时，
应选用的卡环是（）