英语语法分析

The sediment dredging had significant impact on mollusca.

底泥疏浚对螺、蚌等软体动物干扰较大。

Among 52 species of mollusca identified, 45 were gastropods, 7 were bivalves.

调查期间采到的软体动物已鉴定52种，其中腹足类45种，双壳类7种。

The composition of terrestrial mollusca is different except for 10 species 14 genera and 9 families are the same between two areas.

两地区陆生贝类除9个科、14个属、10个种相同外，种类组成存在很大差异。