A、About one week. B、About two days. C、About ten days. D、About four weeks. B事实细节题。短文中提到，修复受损细胞大约需要两天，之后酸痛就会消失。

After a tough workout or a day full of physical activity, it’s common to find your muscles aching. But where do these pains come from? According to a German professor, the soreness comes from straining your muscles in an uncommon way, for example, jumping on a bicycle for a ride, because you haven’t ridden in a long time. Soreness occurs since your leg muscles aren’t used to that movement. When muscles perform an activity they aren’t regularly exposed to, the tiny fibres that are inside them are being torn apart. As muscle soreness develops, the body has to work to repair the muscle tears. But this doesn’t happen immediately. First, the body must realise the muscles are damaged. When the body realises the muscles are hurt, the response is to increase blood flow to the area and increase body heat. Damaged cells are then cleaned up and the body sends cells specially designed to break down the large muscle fibre fragments. Healing can take place after this. It takes about a day until these cells make it to your aching muscles. That’s why there is most often a delay associated with muscle soreness. Repair of damaged cells takes about two days, and afterwards the soreness disappears. Unfortunately, there is little that can be done to relieve muscle soreness. Pain-relieving creams don’t work, but a hot shower or warm bath can provide some relief.
Questions 22 to 25 are based on the passage you have just heard.
22. What does the German professor say about muscle soreness?
23. What happens when muscles are damaged according to the passage?
24. How long does it take for damaged cells to heal?
25. What does the speaker suggest one do to relieve muscle soreness?