-- Who is ____man in a black hat?

-- It’s Jim Black. We often play _______ baseball together in our free time.

A．an, a

B．a, /

C．the, a

D．the, /

较易推广的氟防龋措施是（）

A.含氟才膏

B.氟饮水

C.氟盐

D.氟片

E.氟滴剂