001 Stray birds of summer come to my window to sing and fly away.
And yellow leaves of autumn, which have no songs, flutter and fall there with a sign.
夏天的飞鸟，飞到我窗前唱歌，又飞去了。
秋天的黄叶，它们没有什么可唱，只叹息一声，飞落在那里。
解析一:stray /streɪ/ CET6 TEM4
1.V.If someone strays somewhere, they wa-nder away from where they are supposed to be. 走失
Tourists often get lost and stray into danger-ous areas.
旅游者们经常迷路走进一些危险区域。
2.Adj.A stray dog or cat has wandered away from its owner's home. 走失的 (狗或猫)
A stray dog came up to him.
一只走失的狗来到他跟前。
3.N-COUNT Stray is also a noun. 走失的宠物
The dog was a stray which had been adopt-ed.
这只狗是被收养的流浪狗。
4.V.If your mind or your eyes stray, you don't concentrate on or look at one particular su-bject, but start thinking about or looking at other things. (思想或视线) 不集中
Even with the simplest cases I find my mind straying.
即使对最简单的案例我发现自己的思想也无法集中。
5.Adj.You use stray to describe something that exists separated from other similar things. 离群的
An 8-years-old boy was killed by a stray bullet.
一个8岁的男孩被一颗流弹打死。
以上来源于：《柯林斯英汉双解大词典》
根据译文可知，此处取解释5，形容词，离群的为最佳。
解析二：flutter /ˈflʌtə/ CET6 TEM4
(fluttering, fluttered, flutters)
1.V-T/V-I If something thin or light flutters, or if you flutter it, it moves up and down or from side to side with a lot of quick, light movements. 拍动; 飘动
Her chiffon skirt was fluttering in the night breeze.
她的薄绸裙在晚风中飘动。
...a butterfly fluttering its wings.
…一只拍动着翅膀的蝴蝶。
2.N-COUNT Flutter is also a noun. 飘动; 拍动
...a flutter of white cloth.
…白布的飘动。
3.V-I If something light such as a small bird or a piece of paper flutters somewhere, it moves through the air with small quick movements. 飘舞; 振翅
The paper fluttered to the floor.
纸飘落到地板上。
以上来源于：《柯林斯英汉双解大词典》