A vessel（）when underway shall so far as possible，keep out of the way of a vessel not under command.

单项选择题A vessel（）a crossing vessel，shall not normally enter a separation zone or cross a separation line.

A.including
B.inclusive of
C.except that
D.other than

单项选择题A proper look-out shall be maintained（）.

A.only at night
B.only during restricted visibility
C.at night and during restricted visibility
D.at all times

单项选择题A proper look-out must be kept（）.

A.only in fog
B.only between the hours of sunset and sunrise
C.only when entering and leaving port
D.at all times

单项选择题A head-on situation at night is one in which you see（）.

A.one sidelight of a vessel ahead of you
B.one sidelight and a masthead light of a vessel ahead of you
C.one sidelight，a masthead light，and a range light of a vessel ahead of you
D.both sidelights of a vessel dead ahead of you

单项选择题One of the factors which affects the circulation of ocean currents is（）.

A.humidity
B.varying densities of water
C.vessel traffic
D.the jet stream