Một con lắc đơn có chu kỳ dao động điều hòa là T. Khi giảm chiều dài con lắc 10 cm thì chu kỳ dao động của con lắc biến thiên 0,1 s. Chu kỳ dao động T ban đầu của con lắc là

A. T = 1,9 s.    

B. T = 1,95 s.

C. T = 2,05 s.                 

D. T = 2 s.

Vì sao dây thần kinh tủy được gọi là dây pha ? (1 điểm)

Việc mượn từ trong Tiếng Việt là để:

A. Phát triển từ ngữ Tiếng Việt

B. Biết ngôn ngữ nước ngoài

C. Người Việt Nam đi du lịch

D. Người Việt Nam hiểu văn hoá nước ngoài

Mắt không có tật là mắt

A. khi quan sát ở điểm cực viễn mắt phải điều tiết

B. khi không điều tiết có tiêu điểm nằm trước màng lưới

C. khi quan sát ở điểm cực cận mắt không phải điều tiết

D. khi không điều tiết có tiêu điểm nằm trên màng lưới

To: Kiet

Subject: My activities

Last weekend, I went to Da Nang to visit my aunt. She had a burn on her leg so it's very difficult for her to move. So I came there with my mother to help her with the housework. Moreover, when I came to DN, I went to some supermarkets to play game and do shopping. It's really interesting.

Next weekend, I will go for a picnic with my class. We will go to a beach. This beach that it's very beautiful and the air is very fresh. There, I can swim and play games. I would say that the thing I really look forward to is we can set up a campfire. I'm very keen on about the picnic and now, I have to go to prepare something for the picnic so I will talk to you next time. Bye.

Best wishes for you

Thu

Your best friend

Well, my community now is having a big problem that the streets and the lakes are full of rubbish. Many people see that but they don't care. Personally, I think that if we still let the streets and the lakes are full of rubbish, it will have a bad affect to our health. Therefore, I want to solve this problem by clean up the streets and lakes. On the whole, it's too wonderful if i do that, I think it's too difficult for me to do it alone, so I asked my friends help me to clean up the streets and lakes. And they undoubtedly they will help me. We clean the street and the lake, put all the rubbishes into the waste baskets. Afterall, eveything is great. I feel very happy because I can help our community to become a better place

1. Thanh is tall and thin with long straight hair.

2. They're going to have a meeting at the weekend.

3. His father is generous and friendly.

4. We must not let the children in the kitchen because it is a dangerous place.

5. The Y&Y member is going to take part in a recycling program to save natural and money of the organization.

6. I have a favor that you help me to carry this bag.

7. The town is becoming beautiful.

8. My father used to driving a car to work but now he goes by bus.

9. I spend 2 hours each day to study English.

10. Alexander Graham Bell was born in Edinburgh, on March 3rd, 1847.

1. July

2. February

3. September

4. December

5. November

6. October

7. April

8. August

9. January

10. May

11. March

12. June