"On your desk" 是在你的课桌的英文表达方式。
"On" 是一个介词，表示 "在……之上"。例如：
There's a pen on the table. (桌子上有一支钢笔。)
He put the book on the shelf. (他把书放在书架上。)
"Your" 是形容词，表示 "你的"。例如：
Is this your phone? (这是你的手机吗？)
These are your shoes. (这些是你的鞋子。)
"Desk" 是名词，表示 "课桌"。例如：
I have to do my homework at my desk. (我必须在我的课桌上做作业。)
She sat at her desk and began to work. (她坐在桌子旁，开始工作。)
"On" 是一个介词，表示 "在……之上"。例如：
There's a pen on the table. (桌子上有一支钢笔。)
He put the book on the shelf. (他把书放在书架上。)
"Your" 是形容词，表示 "你的"。例如：
Is this your phone? (这是你的手机吗？)
These are your shoes. (这些是你的鞋子。)
"Desk" 是名词，表示 "课桌"。例如：
I have to do my homework at my desk. (我必须在我的课桌上做作业。)
She sat at her desk and began to work. (她坐在桌子旁，开始工作。)