In such a fierce competition, a person has to make every effort if he________. [      ]

A. has succeeded  

B. is to succeed

C. would succeed  

D. will succeed

男，54岁。阵发性胸痛1月余，均发生于夜间睡眠中，每次持续30分钟。胸痛发作时心电图示ST段一过性抬高，最可能的诊断是（）。

A.急性心肌梗死

B.初发型劳力型心绞痛

C.稳定型心绞痛

D.变异型心绞痛

E.急性心包炎