题目

为了比赛的公平公正，小芸为学校短跑比赛设计了一款防抢跑装置，该装置安装在起跑线前，如图18甲所示，丙图是其工作原理图：起跑发令枪发令前，开关S1、S2、S3都闭合，K与A端相连，绿灯亮；发令枪扳机和开关S2相连动，扣动扳机，枪响同时开关S2断开；当电流表示数小于或等于30mA时，在弹簧弹力作用下，K与A端相连，绿灯亮，无人抢跑；当电流表示数大于30mA时，衔铁被吸下，K与B端相连，红灯亮同时铃声响，有人抢跑。 已知两电路电源电压均Children all over the world like to celebrate their birthdays. American children are of no difference. They usually celebrate with a party. They invite friends to their birthday parties. The party may not be held on the right date of their birthday if it comes on a school day. It may be held on the weekend instead.Today two kinds of parties are the most popular. One is held at home. Parents decorate the house with beautiful balloons and colored paper. They prepare a special birthday meal. The children play games. The other kind is held away from home. Some are at a special restaurant. The children eat pizza and ice cream. The waiters, who serve the food, also sing and tell jokes to the children. Other parties may be held at a park, or at a movie theater, or in some other places.Every birthday party has a cake with candles. There is one candle for each year of a birthday boy’s or girl’s age. When the candles are lighted, everyone sings the special birthday song： Happy Birthday to You.As Americans grow older, their birthday parties change. In fact, many people stop having them. They say they would like to forget how old they are. Yet they do like to keep the happy birthday parties of their childhood in mind.Fill in the blanks according to the passage. Only one word for each blank. （每空一词）Children in the world like having a birthday party at the time of their birthdays. American children are the ______1.________ as others. At that time, their friends are _______2._________ to the parties and the birthday parties are usually held _____3._______ at home or away from home, ________4._______ as at a special restaurant, at a park, or at a movie theater, or in some other places. There are candles for every party. ______5._________ of them stands for one year of the children’s age. But with the children growing, many people want to forget the birthdays.