题目

Grace is a student of a junior high school. She is a good student. She usually gets up at six in the morning. Then she has breakfast.  1   Her mother takes her to school in the car. It takes about half an hour to drive there. The first class begins at seven thirty.  2   She has lunch at school at twelve o’clock. She often has rice and vegetables for lunch because (因为) it’s her favorite food.   3  In the afternoon, classes begin at half past one.  4  She gets home at about a quarter to five and has dinner at six.   5 At about nine thirty, she goes to bed. 根据短 在探究求合力的方法时，先将橡皮条的一端固定在水平木板上，另一端系上带有绳套的两根细绳。实验时，需要两次拉伸橡皮条，一次是通过两细绳套用两个弹簧秤互成角度地拉橡皮条，另一次是用一个弹簧秤通过细绳套拉橡皮条。在两次拉伸橡皮条时，要将橡皮条和绳的结点拉到_______位置,这样做是为了保证合力和分力作用效果的________性。