---His brother John began to study French last year. And now he is good at it. He is so talented.

---_______ He always learns things quickly.

A．So did his brother

B．So is his brother

C．So his brother is

D．His brother so did

下列属于槽形预制钢筋混凝土板的特点的是( )。

A．制作方便

B．造价低

C．隔声效果不好

D．保温效果好