In contrast to the simple observations of the tides, tidal current studies are difficult and expensive.
In contrast to the simple observations of the tides, tidal current studies are difficult and expensive.
与潮汐的简单观测不大相同，潮流研究的难度既大、费用也巨。
In contrast to the simple observations of the tides, tidal current studies are difficult and expensive.
与潮汐的简单观测不大相同，潮流研究的难度既大、费用也巨。