一句现在完成时的句子,求对划线部分提问

问题描述:

一句现在完成时的句子,求对划线部分提问
She has learned 1000 English words since she came.
划线部分为 since she came.

How long has she learned 1000 English words?
注;就since和 ,for 短语提问都是用HOW LONG 提问