It could take 4-6 months before the first batch（批）of vaccines （疫苗）are available to fight A/H1N1 flu ________ as swine flu, WHO officials said.

A．known

B．to know

C．knowing

D．having known

按石化行业规定，循环水检测换热器的流速应为（）。

A.0.5~0.8

B.0.8~1.0

C.1.0~1.5

D.1.5~2.0