_____ are the twins?

They are _____ the classroom. [ ]

A. Where; on

B. How; in

C. Where; in

D. Who; in

流行性腮腺炎为（）.

A.呼吸道飞沫传播

B.粪-口传播

C.血液及注射传播

D.虫媒传播

E.接触传播