mary keeps in touch with her parents by e-mail(by e-mail划线提问）

mary keeps in touch with her parents by e-mail(by e-mail划线提问）
mary keeps in touch with her parents by e-mail(by e-mail划线提问）

mary keeps in touch with her parents by e-mail(by e-mail划线提问）
How does Mary keep in touch with her parents?

How does Mary keep in touch with her parents?