下列哪项最有助于痄腮的诊断（）

A.发热，面颊红肿疼痛

B.血清及尿中淀粉酶升高

C.腮腺管口可见红肿

D.白细胞总数升高

E.腮部红肿疼痛，压之有波动感

I failed in the final exams last term and only then  ____the importance of study.[ ]

A. I realized                    

B. do I realized

C. did I realize                  

D. I had realized