Because of the worldwide breakout of H₁N₁, many countries have placed        on travel to prevent the further spread of it.

1. A.
   criterions
2. B.
   restrictions
3. C.
   descriptions
4. D.
   prescriptions

Because of the worldwide breakout of H₁N₁, many countries have placed        on travel to prevent the further spread of it.

A. criterions                        B. restrictions           C. descriptions                            D. prescriptions

Because of the worldwide breakout of H₁N₁, many countries have placed        on travel to prevent the further spread of it．

A．criterions                B．restrictions             C．descriptions           D．prescriptions

Because of the worldwide breakout of H₁N₁, many countries have placed        on travel to prevent the further spread of it.