题目

若式子有意义，则x的取值范围是（ ） A．x≥3   B．x≤3   C．x＞3 D．x=3 答案：A【考点】二次根式有意义的条件． 【分析】根据二次根式有意义的条件即可求解． 【解答】解：根据题意得：x﹣3≥0， 解得：x≥3． 故选：A． 【点评】本题考查的知识点为：二次根式的被开方数是非负数．Eating habits are different in many countries. The Chinese have a saying， “ Eat good things for breakfast， eat a big meal for lunch， but eat less at dinner.” Many Americans agree that one should start the day with a good breakfast， but their ideas about lunch and dinner are different.Most Americans only give themselves a short time for lunch. So they eat a small meal. After work they will have more time to eat a big dinner. Also a quiet dinner at home with all the family members， talking about their day is a way to rest after a long， hard day of work.Eating at restaurant is also different. In China， people like to talk and laugh while eating. Very often you can hear people talking and laughing loudly， and they are just having a good time. In America it is not like this. People want a quiet place where they can eat a good meal far away from the noise of the outside world. If some people are talking too loudly， the manager（经理） may come out and ask them to leave.1.Which is the good way for keeping healthy in China?A. Eating nothing for breakfast.B. Eating less to lose weight.C. Eating less at dinner.2.How long do most Americans only give themselves for lunch?A. The whole noon.B. A long time.C. A short time.3.Talking at table isn’t a way to rest in America， is it?A. Yes， it is.B. No， it isn’t.C. No. They aren’t.4.What do people like doing when we are having a meal in China?A. Talking and laughing.B. Having a rest.C. Only eating quietly.5.What will the manager of the restaurant do if some people are talking too loudly in America?A. Talk with them happily.B. Let them go away.C. Do nothing.