—Why didn't you go to play football with us yesterday afternoon?

—I _____ my mother with the housework then.   [ ]

A. helped                          

B. was helping

C. had helped                      

D. have been helping

患者，男，31岁，主诉心前区刀割样疼痛、咳嗽，呼吸时加重。体检：T 39.7℃，可闻及心包摩擦音。血 WBC18×10⁹/L，心电图示多数导联ST段弓背向下型抬高，追问病史，2周前有上呼吸道感染史。

最有效的治疗是

A．心包剥离术

B．抗结核

C．足量足疗程杀菌抗生素

D．抗病毒

E．应用激素