如图,△ABC中,AB=AC,∠BAC=40°,D为△ABC内一点,如果将△ACD绕点A按逆时针方向旋转到△ABD′的位置,则∠ADD′的度数是
A:40°
B:50°
C:60°
D:70°
下列有关人体内环境的叙述不正确的是 ( )
English is interesting, _____ I didn't like it at first.