风温与春温鉴别的关键是（）

A.发病季节不同

B.传变方式不同

C.病变部位不同

D.初起临床表现不同

E.发热热型不同

See the flags on top of the building? That was ____ we did this morning.

[     ]

A. when

B. which

C. where

D. what