saliva (唾液) which keeps plaque off teeth, dries up at night, so it's best to have all plaque cleaned off the teeth before sleep.__5__

　　A．Make sure it's alcohol free.

　　B．Apples are good, as are raw carrots, celery and popcorn.

　　C．Otherwise, you're just transferring bacteria to your mouth.

　　D．However, the bacteria won't be staying on the top of your tongue.

　　E．It's more effective than brushing your tongue with a toothbrush too.

　　F．When you sleep without bacteria in your mouth, you will feel much better.

　　G．It's also important to brush first in the morning to remove plaque and bacteria built up as you slept.

　　1．解析：选C　根据此空前的"Throw away your toothbrush ... every two to three months."可知，每隔两到三个月要换一次牙刷，本空应说明这样做的原因。C项(否则你就是在把细菌转移到嘴巴里。符合语境。)

　　2．解析：选E　根据空前的"One cause of bad breath ..., which a daily tongue scraping will help banish(清除)．"可知，刮舌板有助于有效清除舌头上堆积的细菌，故此处描述的是刮舌板的益处。E项意为"这比用牙刷刷你的舌面更加有效"，符合上下文逻辑。其中it 指代Use a tongue scraper every morning ...这件事。

　　3．解析：选B　根据空前建议吃有清洁作用的硬的或脆的食物，边咀嚼边清洗牙齿可知，此段应涉及所吃的食物。只有B项中出现了食物。故选B项。

　　4．解析：选A　根据本空后的"Mouthwashes with too much alcohol can dry out mouth tissue ..."可知，此处应是建议使用不含酒精的漱口水。故选A项。

　　5．解析：选G　根据最后一段，建议起床后第一件事和睡觉前最后一件事是刷牙，以及本空前描述要在睡觉前刷牙可知，此处应该是早晨起来也要刷牙。G项意为"同样重要的是早晨起来先刷牙，以此来清除夜间睡觉堆积起来的牙菌斑和细菌"，符合逻辑。故选G项。

　　Ⅲ.完形填空

　　Years ago, feeling tired and frustrated，I began to doubt whether teaching was worth it anymore.__1__， a ridiculous moment in class lit my way out of the darkness.

　　I was teaching a chemistry lesson, and the students were__2__ about working with alcohol lamps.But a girl couldn't get her wick (灯芯) to burn. She was one of the kids who always seem to be the __3__ one picked for the team, who appeared to have__4__ that she could never be special.

　　Normally I do not interfere with science projects, because__5__ can be part of the learning process.Yet this was simply a matter of faulty equipment；the wick was not as __6__ as it should have been.I needed to __7__.

　　The girl had tears in her eyes, and I felt__8__ of myself for ever having felt like giving up. For that one moment, the only thing that__9__ to me was that this girl should have a successful experiment.She was going to go home that day with a __10__ on her face.I bent over her alcohol lamp, and with a long kitchen match tried to reach the wick.I was so __11__ to the match that I could feel the flame.Finally the wick caught fire, and I looked up triumphantly (得意扬扬地), __12__the smile on the girl's face.

__13__， she took one look at me and began screaming in fear.I did not understand why the kids were all pointing at me__14__ I realized that the flame had lit my hair.Several kids ran to me and __15__at my head.Talk about a dream come