（）左右开始学习刷牙的习惯
A、半岁左右
B、1岁左右
C、1岁半左右
D、两岁左右
参考答案：C
已知菱形ABCD的周长为20cm，且相邻两内角之比是1：2，求菱形的对角线的长和面积。
The president was so absorbed in his work that not a sound ______. [ ]
A. did she dare to make
B. dared she to make
C. she dared make
D. she did dare to make
