A.in useB.prior to useC.after useD.When chart received ……

单项选择题What is the distance from the bottom of a wave trough to the top of a wave crest?（）

A.Wave length
B.Wave height
C.Wave breadth
D.wave depth

单项选择题Depths in the routes (Malacca and Singapore Straits) vary between 20m and about 23m but there are many areas of sand waves and depths are liable to change. The statement infers that（）.

A.depths in Malacca and Singapore Straits are stable
B.depths in Malacca and Singapore Straits are changeable
C.depths in Malacca and Singapore Straits are invariable
D.depths in Malacca and Singapore Straits are the same all the time

单项选择题The lifeboat is constructed of（）

A.totally enclosed
B.glass-reinforced plastic
C.self-righting
D.powered

单项选择题Deep-draught vessels and VLCCs shall allow for（）of at least 3.5 m at all times during the entire passage through the Straits of Malacca and Singapore.

A.a draft
B.a freeboard
C.an air draft
D.an under-keel clearance

单项选择题Vessel must be（）duly qualified officers and crew.

A.supplied with
B.equipped with
C.manned with
D.fitted with