A wave entering（）is likely to produce bores．

（）is not a type of tide.

A.SEMIDIURNAL
B.DIURNAL
C.MIXED
D.OSCILLATING

点击查看答案&解析

Water may boil up around the stern of a vessel in a channel due to（）.

A.slack water when upbound
B.shallow water
C.a cross current
D.a head current

点击查看答案&解析