题目

如右图所示是某物体运动全过程的速度—时间图象．以a1和a2表示物体在加速过程和减速过程中的加速度，以x表示物体运动的总位移，则x、a1和a2的值为( ) A．30 m,1.5 m/s2，－1 m/s2 B．60 m,3 m/s2，－2 m/s2 C．15 m,0.75 m/s2，－0.5 m/s2 D．100 m,5 m/s2，－3 m/s2     答案：【解析】 总位移x＝ m＝30 m．加速时 a1＝＝ m/s2＝1.5 m/s2，减速时a2＝＝ m/s2＝－1 m/s2. 【答案】 A根据下列句子的意思及所给单词的首字母或汉语提示，写出所缺单词，每空限填一词。1. Help y_________ to some cakes, children. 2. In most western countries, people don't eat with c_________, they use knives and forks. 3. I'm _________ (渴的), I want to buy a bottle of water. 4. Mid-autumn Festival is one of the Chinese t_________ festivals. 5. She's _________ (分) the watermelon into twenty pieces and given them to each student.