Which condition represents the appropriate time for setting off distress flares and rockets? （）

A.At one hour intervals

B.At half hour intervals

C.Only when there is a chance of their being seen by rescue vessels

D.Immediately upon abandoning the vessel

1858年，即美国之后，荷、俄、英、法等列强又与日本签订了一系列不平等条约，史称（）。

A.“日美修好通商条约”

B.“安政五国条约”

C.“日美亲善条约”

D.“日美友好条约”