After a 5-year absence, we returned to our mother school, and not until then       it was such a beautiful school.

A．we realized

B．had we realized

C．we had realized

D．did we realize

通过皮肤-直肠反射，促进感觉反馈传入和传出属于直肠训练的（）

A.肌肉的训练

B.直肠感觉的再训练

C.腹部按摩

D.肛门牵张术

E.生物反馈术