根据短文理解，选择正确答案。
Down by the salley gardens
my love and I did meet;
She passed the salley gardens
with little snow-white feet.
She bid (请求) me take love easy,
as the leaves grow on the tree;
But I, being young and foolish(傻的),
with her would not agree.
In a field by the river
my love and I did stand,
And on my leaning shoulder(肩膀)
she put her snow-white ______.
She bid me take life easy,
as the grass grows on the weirs(河堰);
But I was young and foolish,
and now am full of tears(眼泪).
含有氧气分子的是（ ）