keels
n. 龙骨（keel 的复数）：船或船只的主要结构支撑，位于船体底部，从船头延伸到船尾。
· The ship's keels were made of strong wood.
这艘船的龙骨是由坚固的木头制成的。
例句
The caudal peduncle is very slender and includes three sets of keels.
尾端的花梗很细，包括三组龙骨。
As only a very general rule, most sailboats over 20-something feet have fixed keels.
作为一条通常规律，大部分20英尺以上的帆船使用固定龙骨。
Sailboats have many different types of fixed keels, such as full keels (see photo) and fin keels.
帆船有许多种不同类型的固定龙骨，例如全龙骨(见上图)及鳍板。
