I could see the greyish feathers of its flanks.是什么意思？

I could see the greyish feathers of its flanks.

我看见了它两胁间斑白的羽毛.

could

aux. “can”的过去式，能够，打算，用于假设语气的条件句，用于虚拟语气的结论句；

例句
The regulations were relaxed and the prisoners could get out and about a bit.
规定有所放宽，犯人可以出去短暂放风。

see

vt.& vi. 看见，领会，理解，查看，参观；n. 主教教区，主教权限，牧座；

例句
Anyone from the houses across the road could see him...
马路对面房子里的任何一个人都能看见他。

the

art. 指已提到的人（物），指说话人与听者已知的人（物），用于独一无二的事物前，与形容词最高级和序数词连用；

例句
He did have a real knowledge of the country...
他对该国的确知之甚多。

greyish

adj. 带灰的，略灰的；

例句
Between the white limestone and the greyish pink limestone is a thin bed of clay.
在白色石灰石和粉灰色石灰石之间是一层薄薄的黏土。

feathers

n. 羽毛( feather的名词复数 )；

例句
The tail feathers are dark blue at their bases, shading to pale blue at their tips.
尾羽的根部呈深蓝色，到了尾尖就渐变成淡蓝色。

of

prep. 关于，属于…的，由…制成；aux. 助动词 [非标准用语、方言] =have [主用于虚拟语气]；

例句
He did have a real knowledge of the country...
他对该国的确知之甚多。

its

pron. (it的所有格形式)它的，厥；

例句
The government is to accelerate its privatisation programme.
政府将加快其私有化计划的进程。

flanks

n. 胁( flank的名词复数 )，侧腹，侧边，侧

例句
The horse's flanks are hurt.
马的两肋受了伤.