小儿，5岁，20天来消瘦，乏力，低热。查体：颈部淋巴结肿大，肺无啰音，肝肋下2cm，结核菌素试验（++）。胸片：右中上肺可见哑铃状阴影。诊断为（）

A.支气管肺炎

B.浸润性肺结核

C.粟粒性肺结核

D.支气管内膜结核

E.包括原发综合征和支气管淋巴结核

It was not until he became very ill ______ he went to see a doctor.

A．what

B．that

C．when

D．then