完形填空

    When you live in a seasonal environment, you can learn that both outdoor and indoor activities have their place. As the seasons1 so does your mood. Certain activities become more or less attractive2 the weather and the length of the day.

    Spring is a time of the year when the world starts to3 from its winter sleep. During this season, I enjoy going on long walks through parks and watching the world come4.

    Many consider summer to be the top of the year. The city comes into full swing5 the weather becomes warmer and warmer. During the summer, I prefer to spend the daytime anywhere that is air-conditioned. This 6include the library, a shopping center or a movie theater. I often enjoy spending the7evenings sitting on the wide balcony of my house and having drinks with my friends.

    Fall, with the8 of the leaves and the summer heat gradually 9is probably another 10 time to go on long walks during the day. I love to be 11during fall and see the life of the city returning to its hibernation (冬眠). Another12to go outside during autumn is to 13the last days of warmth until the next year.

    Winter14 the shortening of days and cooler weather. Outdoor activities tend to become less 15 and sinking down on the sofa with a good book becomes my16 activity. It is not enjoyable to spend time outside if it is too 17I only choose to go outside when I want to go skiing.

    So, my 18to spend time indoors or outdoors is vastly dependent on the19. Different seasons 20different activities and therefore it is Impossible to choose whether I would spend all of my spare time indoors or outdoors.

甲、乙两人共同生产某种零件，若甲先生产1天，然后两人又一起生产了5天，则两人生产数量相同；若甲先生产300个，然后两人同时生产4天，则乙比甲多生产100个零件。设甲、乙每天分别生产 $x$ 个和 $y$ 个零件，根据题意，可列方程组____。

阅读短文，从每小题所给的四个选项中，选出正确的选项。C
    Prana was my close friend, whose name means "bright boy in life." Although he died several years ago, I can still remember the days we spent together and what he taught me about love.
    I have two apple trees in the garden. Prana loved apples. When he went outside, he'd catch an apple and take it into the house to eat later. The apples had been on the ground and were often dirty so I wasn't always happy that Prana had brought them into the house.
    It was an autumn day in Britain, but it was very cold. A big snow fell and we had not done anything for its coming. On that special day, Prana went outside and I watched him through the window. I noticed that he was madly digging holes and bringing the apples to the ground so they could be seen above the snow. I did not know why he was doing this. It seemed that he wanted to do something special.
    When I called him back, he had his usual one apple in his mouth. About five minutes later, I looked outside. The garden was covered with birds. Prana had dug up all those apples for his birds' friends to eat. He knew that they wouldn't have stored enough food for the coming winter! It is just a dog who did such a great thing.

如图所示四个声现象中，哪两个可以用相同的声学知识解释（　　）

已知四边形ABCD是⊙O的内接四边形，AC是⊙O的直径，DE⊥AB，垂足为E．