下列各句中，没有语病的一句是( )

You can’t imagine the difficulty he ____ into the cold river and saving the drowning girl. [ ]

nlinegames are full of violence, which do harm to the development of thechildren. —-And that’s_______ my concern lies.

It is these poisonous products ______can cause the symptom of the flu, such as the headache and aching muscles.

What about the new medicine for you?—The medicine_______. I’m better now.