Đọc kỹ đoạn văn rồi trả lời mỗi câu hỏi.

You may use the telephone every day but how much do you know about it? The telephone was invented by Alexander Bell in 1876. Bell was born in Scotland in 1847. Later he went to live in the US. Alexander Bell was always interested in sound. He wanted to be able to send sound through a wire. He had a workshop in his house in America and did many experiments there. One day, while he was doing an experiment in his workshop, he was careless and spilt some burning liquid onto his clothes. Talking into his telephone, Bell said: “Mr. Watson, I want you to come over here immediately, please.” His assistant, Watson, was in another room far away from the workshop. However, he heard Bell clearly on his own telephone. Quickly, he ran to Bell’s workshop. “Mr Bell, I heard every word you said!” Watson shouted excitedly. Bell finally succeeded. He had invented the first telephone. Later other inventors made better ones.

1. When was the telephone invented ?

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Nếu AB = 120 km

Thời gian xe thứ nhất đi là: 2 giờ chiều - 8 giờ sáng = 14 giờ - 8 giờ = 6 giờ

=> Vận tốc xe thứ nhất: 120 : 6 = 20 hm/h

Lúc 9 giờ xe thứ nhất đã đi đc 20 km, thời gian để xe thứ hai đuổi kịp xe thứ nhất là: 20/20 = 1 giờ. 

Khi đó xe thứ nhất đi được: 1 giờ + 1 giờ = 2 giờ.

chỗ gặp nhau cách A là: 20 x 2 = 40 km

Nếu AB = 240 km

=> Vận tốc xe thứ nhất: 240 : 6 = 40 hm/h

Lúc 9 giờ xe thứ nhất đã đi đc 40 km, thời gian để xe thứ hai đuổi kịp xe thứ nhất là: 40/20 = 2 giờ. 

Khi đó xe thứ nhất đi đc 1 giờ + 2 giờ = 3 giờ.

Khi đó chỗ gặp nhau cách A là: 40 x 3 = 120 km

Như vậy đáp số phụ thuộc vào quãng đường AB

hình 1

chia động từ:

I'm very busy so I can't help you. If I( not be ).............so busy , I help you.

chia động từ:

when I (arrive )...... at the train station yesterday, I(meet).......... by my uncle and aunt

Have they told you anything about it?