MRI可显示下列心脏结构，除了（）
A.房室间隔
B.心肌壁厚度
C.心腔大小
D.人工生物瓣膜
E.金属瓣膜
参考答案：E
He often_______ tennis with his friends. Now they_______ tennis at school.
A．play; play
B．plays; playing
C．plays; are playing
D．playing; are playing
