一

    味精在都市传说中具有许多危害，版本也不尽相同。许多人“相信”味精有害，很重要一个原因认为它是“化学工业品”。虽然味精亮晶晶的，好像一种化工产品，其实它和酱油、醋一样，都是一种酿造产品，可以增进人们的食欲，提高人体对其他各种食物的吸收能力，对人体有一定的滋补作用。

    味精的诞生和使用只有百年的历史，但对于拥有几千年历史的美食大国而言，没有味精，依靠各种天然食材混搭也能提出鲜味来。据说，古时“鲜”字的写法本是三个鱼字。鱼本鲜中之最，三个鱼就更鲜了。春秋时代齐桓公的御厨易牙首创了“鱼腹藏羊肉”这道菜，从而开创了天然食材混搭提鲜之道。

    古人最常用的是食材混搭煮制高汤提鲜，俗话说，“艺人的腔，厨子的汤”，制作出优质的清汤或奶汤，是使菜肴增鲜的最佳手段。在发明味精前，高汤几乎是全世界每一个专业后厨的必备品，用高汤代替水是让菜品变得更加鲜美的利器。中餐的开水白菜、鱼翅捞饭需要鸡肉火腿清汤和鸡爪猪肉浓汤；日料寿喜烧、茶碗蒸需要柴鱼昆布高汤“出汁”；意大利炖饭需要鸡高汤；西班牙海鲜饭需要鱼或者海鲜高汤；当然还有各国素食里的素高汤等等。

    制汤俗称“吊汤”，可以追溯到1400年前“捶牛羊骨令碎，熟煮，去汁；掠去浮末（沫），停之使清”（《齐民要术》）的制汤法；后来出现了一种“捉（提）清汁法”，其做法是：将鸡汤、鸭汤或肉汤放在锅中烧煮，然后将生虾捣烂，和入甜酱、酱油，再投进汤中，等汤沸腾，泛起浮沫，即撇去。如此三四次，捞去虾渣，即成清汤。

    除了采用高汤提鲜外，古人常将蟹肉、蟹油、蟹黄用猪油“炼”后收贮起来，俗称“蟹油”，供制作肴馔时用。这种方法，江苏、浙江民间至今仍颇盛行。无论烧菜、制馅，还是下面条，都可以放入适当的“蟹油”，其味之鲜，不可言传。

    此外，古人还常将一些比较鲜美的食品原料磨成粉，制作成原始的“味精”撒在菜肴中以增鲜。如清顾仲所撰的《养小录》中就记有用笋粉和蘑菇粉提鲜。清朝时期的鲁菜成为宫廷菜的重要原因，鲁菜师傅能从各种海鲜里提出鲜味来，比如将海肠子烘干研磨成粉，做菜时撒进去，这种原始的“味精”使得普通的菜肴立马变鲜。

二

    1908年，一位名叫池田菊苗的日本东京大学化学教授在喝了妻子做的海带黄瓜汤后，发现味道特别鲜美。“海带和黄瓜都是极普通的食物，怎么会产生如此的鲜味呢?”池田充满了疑问。从这天起，池田教授就在实验室里仔细研究起海带的成分来。半年后，他从10公斤海带中提取出0.2克谷氨酸钠，只要在汤里放一点点这玩意儿，立刻就能增加汤的鲜味。

    谷氨酸钠是一种氨基酸——谷氨酸的钠盐，谷氨酸是组成蛋白质的20种氨基酸之一，只要食物中含有蛋白质，就含有谷氨酸。但是结合在蛋白质中的谷氨酸是没有味道的，只有当谷氨酸游离出来时才能刺激舌蕾上的鲜味受体，谷氨酸由酸变成盐时更容易电离，也就更有鲜味。

    其实谷氨酸钠最早是1866年由德国化学家里德豪森研制成功的，他当年是从植物蛋白中提取的这种成分，由于技术条件的限制，当时这种产品在欧洲并没有批量生产。池田菊苗认识到了谷氨酸钠的商业价值，想到了该怎样用工业方法生产谷氨酸钠。当时一位名叫铃木三朗助的日本商人，正和他人共同研究从海带中提取碘的生产方法。当他看到池田教授的研究成果后大为振奋，立刻决定生产谷氨酸钠。池田和铃木的合作很快就结出了硕果。不久后，一种叫“味之素”的商品出现在东京浅草的一家店铺里，广告语是“家有味之素，白水变鸡汁”。一时间，购买“味之素”的人差点挤破了店铺的大门。

三

    “味之素”传入中国后，这种奇妙的白色粉末让日本企业获得了巨额收益，日本人对谷氨酸钠的提取工艺严格保密，企图长期垄断全球市场。1921年，一位名叫吴蕴初的中国人利用空余时间，和夫人一起，在上海租用的一处住房的阁楼里，开始研制提取谷氨酸钠的技术，经过不懈努力，他发明了生产谷氨酸钠的水解法。

    工艺成功后，吴蕴初寻找投资人合作建立了“天厨味精厂”，并且在吴蕴初的提议下，采用了至今仍在使用的“佛手”商标。天厨味精厂的佛手牌味精一上市，立即打破了日本“味之素”的垄断。从此，味精进入了中国普通民众的厨房，并随着中餐在世界范围内的普及，和中华饮食文化永久联系在了一起。

    20世纪60年代，被称为“台湾发酵之父”的苏远志利用生产蔗糖的废糖蜜作为细菌发酵生产味精的培养基质，大大降低了味精的生产成本，而且增加了产量。因为苏远志的发明，60年代我国台湾地区每年节省进口小麦外汇400万美元，同时外销味精赚进600万美元。到了1981年，我国台湾味精外销量达12353吨，取代日本跃居世界首位。

——节选自母冰《味精：舌尖之鲜的奥秘》

A. Be a good listener.  B. Care about the details.

C. Strike up a conversation. D. Make time for friendships.

E. Reach out to the newcomers.    F. Avoid causing inconveniences

    Develop Better Relationships with Neighbors

    Good neighbors are a lot like electricity or running water：we don't know how much we depend on them until we don't have them. They make our lives more pleasant and give us a sense of who we wrte, both as an individual and as a member of the community. Here is how to develop your relationships with these very important people in your life.

    ____ Often neighbors don't even know each other's names. But it's okay to be the one to break the ice , even if you've lived next door for years.Most neighbors enjoy making small talk with the folks on the other side of the fence. So as you see them at work in their yards, smile, wave, and say hello. Ask how their kids are (whether they're babies or in college), whether they could use an extra cucumber from your garden, or what they think of the price at the local supermarket.

    ____ These days, the old Welcome Wagon is a thing of the past. But your new neighbors may be feeling lonely and unsure, especially if they're far from home, and might appreciate a friendly face bearing fresh-baked chocolate cakes. If they have kids, tell them where the children in the neighborhood live. Recommend the best places to eat and sleep. Invite them over for coffee or tea when they get settled, give them your number, and point to your house as you say good-bye.

    ____ Return anything that you borrow from a neighbor, such as tools, in good repair and as soon as you've finished with them. Replace anything that belongs to your neighbor that you, your children, or your pets break or soil. Make sure that your car is not blocking their doorway. Such random acts of consideration will have your neighbors talking—and the talk will be good.

    ____ If you value a friendship with your neighbors, spend time with them. What better way to meet your neighbors than to invite them to an informal barbecue, pool party, or holiday open house? Better yet, you might even consider throwing a get-together in their honor. Deliver the invitations in person to everyone who lives on your street and chat with each for five minutes before moving on to the next house. This way, you will get an idea of what your neighbors are like so that you can plan for appropriate food and music.

    ____ In a good relationship, it's really the little things that count. Help to bring in the mail for the elderly neighbor when there is a heavy rain. When your neighbor gorgets to take in his rubbish cans, roll them back into his yard. If you're truly concerned, you'll know when your neighbor needs some cheering up—a bunch of flowers or a helping hand when it's needed. All it takes to develop your relationship with neighbors is the respect for their feelings.

在临床治疗上已证实，将受SARS病毒感染后治愈患者（甲）的血清，注射到另一SARS
患者（乙）体内能够提高治疗效果。甲的血清中具有治疗作用是（     ）

已知∠α=30°，那么∠α的余角等于（　　）