-Your brother speaks English very well.
-Yes, so he does. He practices _______ English every day.
A:speaking
B:speak
C:speaks
D:to speak
图中A、B、C、D依次表示消化道相邻的几个器官,曲线X、Y、Z表示三大类有机物在上述器官中被消化的程度.下列叙述正确的是( )
元朝时民族融合进一步加强,最主要的原因是( )