你好.我明白你的意思.
在比较地道的英语中,而不是在学生英语中,这个句子-------There is a pen on the desk which Mother bought for me the other day. --------如果一定要倒装,可以改写成：On the deskis a pen which Mother bought for me the other day.当然也可以写成：On the desk there is a pen - -- - ,但这是为学习英语而设计的学生英语,在语法上也是对的.