cho vật sáng AB có dạng mũi tên,đặt vuông góc với trục chính 1 tkht (điểm A nằm trên trục chính), cách thấu kính hội tụ 1 đoạn 48cm, thì thu được ảnh A'B' ngược chiều với AB và cách quang tâm của TKHT một khoảng bằng 24 cm. a) Vẽ hình và xác định đầy đủ quang tâm, tiêu điểm của TKHT b) Tính tiêu cự của thấu kính này.

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Take a Bath! Traveling is fun because you can see how people in other parts of the world live. One thing travelers don’t often think about before traveling is how other cultures bathe. And bathrooms in many countries may be different from the kind you are used to. In the United States, most people take a shower once a day in the morning. The showerhead is usually mounted on the wall and cannot be moved. The bather simply stands under the water, gets wet, scrubs with soap and often a washcloth, and then rinses off. Children often take a bath each night and enjoy playing with small toys such as boats and rubber ducks. Many adults, especially women, enjoy a soothing bath to get rid of stress at the end of the day. It is important to remember that when you take a shower or bath in the United States, you should be careful to keep the water inside the bathtub or shower. Unlike bathrooms in many countries, there is no drain in the floor. If water gets on the floor it cannot go anywhere and must be cleaned up with a towel or mop. It can also cause problems for the floor. So be careful. 1. What the traveller don’t often think about? _______________________________________________________________ 2. When do Americans often take a shower? _______________________________________________________________ 3. What about children? When do they take a bath? _______________________________________________________________ 4. What should you remember when taking a shower or bath in the United States? _______________________________________________________________ 5. Do you think that taking a bath can get rid of stress at the end of the day? _______________________________________________________________