题干

在△ABC中,| AB→ + AC→ |=| AB→ ﹣ AC→ |,AB=4,AC=2,E,F为线段BC的三等分点,则 AE→ • AF→ =(   )

A:109

B:4

C:409

D:569

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C

同类题1

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      The freezing Northeast hasn't been a terribly fun place to spend time this winter, so when the chance came for a weekend to Sarasota. Florida. my bags were packed before you could say “sunshine. I left for the land of warmth and vitamin C(维生素C), thinking of beaches and orange trees. When we touched down to blue skies and warm air, I sent up a small prayer of gratefulness.Swimming pools, wine tasting, and pink sunsets(at normal evening hours, not 4 in the afternoon) filled the weekend, but the best part—particularly to my taste, dulled by months of cold­weather root vegetables—was a 7 a.m. adventure to the Sarasota farmers'market that proved to be more than worth the early wake­up call.

      The market, which was founded in 1979, sets up its tents every Saturday from 7 a.m. to 1 p.m., rain or shine, along North Lemon and State streets.Baskets of perfect red strawberries; the red­painted sides of the Java Dawg coffee truck; and most of all, the tomatoes:

amazing,large,soft and round red tomatoes.

      Disappointed by many a broken, vine­ripened(蔓上成熟的) promise, I've refused to buy winter tomatoes for years. No matter how attractive they look in the store, once I get them home they're unfailingly dry, hard, and tasteless.But I homed in, with uncertainty, on one particular table at the Brown's Grove Farm's stand,full of fresh and soft tomatoes the size of my fist.These were the real deal—and at that moment, I realized that the best part of Sarasota in winter was going to be eating things that back home in New York I wouldn't be experiencing again for months.

       Delighted as I was by the tomatoes in sight, my happiness deepened when I learned that Brown's Grove Farm is one of the suppliers for Jack Dusty, a newly opened restaurant at the Sarasota Ritz Carlton, where—luckily for me—I was planning to have dinner that very night.Without even seeing the menu, I knew I'd be ordering every tomato on it.

同类题4

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    A Hobby is a regular activity that is done for enjoyment, typically during one's leisure(闲暇的) time. By continually taking part in a particular hobby, one can acquire practical skill and knowledge in that area. Is travel a good hobby? Travel, in the youngest sort, is a part of education and, in the elder, a part of experience. Some may think otherwise. To them, visiting churches, castles, libraries, etc. is an absolute wastage of time. They may further say that one can read the account of these or see the films of the important places of the world. They forget that touch of actuality gives a different type of sensation and satisfaction.

    Travelling may be an expensive hobby but it makes up for the financial loss. If a traveller has interest in life and its manifestations(表现), one can find much to keep oneself absorbed and happy. A student of any stream can definitely find something of his own interest and studies. One can definitely find everything that satisfies his cravings for knowledge and feelings.

    As a hobby, travelling keeps us busy during leisure time; it is the best method to make use of time. Till a person breaks from dull routine, physically and mentally, one cannot find satisfaction. Travelling helps us to achieve this break. At a new place, one is curious to know and eager to gather all the unknown information about the place which he has neither read nor heard before and he gets thrills and surprises which keep the interest and enthusiasm alive and encourage us to keep our journey on.

    While travelling, one comes across a number of people from varied backgrounds and places. By interacting with them, he comes to know about their traditions also. In case one has psychological bent of mind, one increases one's experience and power to understand others. Understanding human nature is, perhaps, the best part of education. Travelling satisfies all demands of a good hobby-it is absorbing education and refreshment to the mind, body and soul.