Peter received a letter just_____his grandma would come to see him soon.[ ]

A. said                      

B. says

C. saying                    

D. to say

尿毒症脑病的发病原因是（）

A.血中尿毒症毒素蓄积

B.脑循环和脑代谢障碍

C.水、电解质平衡失调

D.代谢性酸中毒

E.以上各种因素共同作用