搜题请搜索小程序“爱下问搜题”
问题
单项选择题
龈下牙石是
A.形成较快,质地较松的牙石
B.沉积于牙周袋内根面上的牙石
C.沉积于龈缘以上牙面的牙石
D.肉眼可见,呈浅黄色
E.用器械较易去除的牙石
答案
参考答案:B
解答题
18
-
1
2
÷
2
-1
+
1
2
+(
2
-1
)
0
.
查看答案
选择题
Mr. Black said, "I have walked a long way this week." Mr. Black said that ______ a long way ______.
A. I had walked; last week.
B. he had walked; that week.
C. I walked; last week
D. he has walked; last week.
查看答案