We finished the job last night ,but it was already midnight _______I arrived home．

A．while

B．when

C．where

D．that

Ⅰ级（轻度）慢性阻塞性肺疾病的标准是（）

A.有或无慢性咳嗽、咳痰症状

B.伴慢性呼吸衰竭

C.FEV₁／FVC<70％

D.FEV₁<70％

E.FEV₁≥80％预计值