阅读下列短文，从文后各题所给的四个选项中选出一个最佳答案。

     Hearing is very important to all of us. We can 1beautiful music, nice songs of birds, the laughter of people or other different kinds of  2 in the world with our ears. 3 we must try to protect our ears. The following will tell you  4 protect ears.

    Listening to 5 usic a lot can be bad forears, especially when headphones are used. So 6 the volume(音) when you're wearing headphones or try not to wear headphones. You should give your ears a rest if you like wearing headphones.

    Before swimming, remember 7 earplugs （耳塞) into your ears or wear a swim hat to stop water from getting into your ears.

If you are going to a concert, wear earplugs to protect your ears 8 the terrible music! In fact, special earplugs can be made for you if you go to concerts a lot or if you are a musician yourself.

    See a doctor if your ears 9. Take some medicine if the doctor asks you to do so. Follow the advice above now and you won't be saying"what?"when you are getting 10.

2016年11月30日，中国二十四节气正式成为世界非物质文化遗产。将二十四节气最早定于历法的是公元前104年制定的《太初（汉武帝年号）历》。当时的中枢权力体系为(    )

为了探究细菌对植物遗体具有分解作用，某校生物兴趣小组的同学设计了如下两套实验方案：

方案一：将同一树的部分落叶进行灭菌处理后，平均分成甲、乙两组，甲组接种细菌，乙组不接种细菌，两组都放在无菌环境中，实验过程中都添加蒸馏水，使树叶保持湿润．

方案二：取两种树的等量落叶，分别标为丙组和丁组，将两组落叶进行灭菌处理后，丙组接种细菌，丁组不接种细菌，两组都放在无菌的环境中，两组在实验过程中都添加蒸馏水，使树叶保持湿润．

请根据上述实验方案，回答下列问题：

如图所示，S为发光点，试画出经平面镜MN反射后通过A点的反射光线和相应的入射光线。