题目

数列{(－1)n?n}的前2 013项的和S2 013为( )A. －2 013 B. －1 017C. 2 013 D. 1 007 答案：【答案】D【解析】S2 013＝－1＋2－3＋4－5＋…＋2 012－2 013＝(－1)＋(2－3)＋(4－5)＋…＋(2 012－2 013)＝(－1)＋(－1)×1 006＝－1 007.本题选择D选项.A. Read and choose the best answers. Eating habits are often different in many countries. It’s very helpful to know something about the British meals before travelling to Britain. In many English houses, people eat four meals a day. They are breakfast, lunch, tea and dinner.Breakfast takes place at any time from 7:00 to 9:00 in the morning. They usually have eggs, bread with butter, cheese and so on. English people drink tea or coffee at breakfast. Lunch comes at one o’clock. It can be a hamburger or a three-course （三道菜的）meal. Afternoon tea is between 4:00 p.m. and 5:00 p.m. Dinner begins at about half past seven. The first course is soup. The next is often meat or fish with vegetables. Then come fruits of different kinds; apples, pears, bananas and so on.But not all English people eat like that. Some of them have dinner in the middle of the day. Their meals are breakfast, dinner, tea and supper. And all these meals are usually simple.【1】The English usually eat ________ a day.A. two mealsB. three mealsC. four mealsD. five meals【2】English people usually drink ________ for breakfast.A. orange juiceB. milkC. teaD. tea or coffee【3】In Britain, afternoon tea often takes place ________.A. before lunchB. between breakfast and lunchC. after dinnerD. between lunch and dinner【4】The second course at dinner is often ________ at British meals.A. soupB. cheeseC. meat or fish with vegetablesD. bread with butter【5】Some English people have meals a day. They are .A. breakfast, lunch, dinnerB. breakfast, dinner, tea and supperC. lunch, dinner, supperD. tea, lunch, supper