-Do you know the boy       is sitting next to Peter?

-Yes,He is Peter’s friend,They are celebrating his        birthday.

A．/;nineth

B．that, nineth

C．who,ninth

D．who,the ninth

细胞水肿()

A．是一种轻度的损伤

B．电镜下线粒体肿胀

C．病因消除后可恢复正常

D．可称为气球样变

E．细胞体积较正常大