b) My friend wasn't waiting for me when I arrived late. 7.a) When did he have the accident? -As he was climbing up the ladder. b) When was he having the accident? -As he was climbing up the ladder. 8.a) l read a book when she sent me an SMS. b) l was reading a book when she sent me am SMS. 9.a) Did you eеat lunch when the fire alarm rang? b) Were you eating luncn when the fire alarm rang. 10.a) lt was a beautiful day The sun shone and there wasn't a cloud in the sky. b) lt was a beautiful day. The sun was shining and there wasn't a cloud in the sky.
Look at the of sentences below. Both of them are grammatically correct. Choose one sentence in each pair, a or b, that is more logical. 1.a) lt rained heavily when I ran for the bus. B) lt was raining heavily when I ran for the bus. 2.a) The rain jjust came into the station when we arrived on the platform. b) The train was just coming into the station when we arrived on the platform. 3.a) He broke his leg while riding his bike at the weekend. b) He was breaking his leg while riding his bike at the weekend. 4.a) While I was watching TV, someone knocked on the window. bjWhile I was watching TV, someone was knocked on the window. 5 a) No wonder she fell off her bike. She didnt Innk here che iwac in
6 Complete the sentences with when or while. 1) The boys were playing football ... the ball flew into the window. 2) Ronny was painting the fence ... the bucket of paint turned over. 3) Denny was putting a tent ... the girls were gathering wood for fire. 4) Rita was sleeping .. the alarm- rang. 5) Nelly was peeling potatоes her sister was cutting chicken into pieces. 6) Nigel was skiing he fell down and broke his leg. 7) They were arguing ... Mrs Elliot entered the room. 8) ... my mother was watching her favorite show on TV, father making coffee. 9) She was tying a letter some mistakes. 10) They were driving towards the village it started clock she found to snow.
Велосипедист движется по дороге эта дорога состоит из горизонтальных, восходящих и нисходящих участков. Скорость велосипедиста составляет 10 км/ч по горизонтальной дороге, 6 км/ч по дороге в гору и 15 км/ч на спуске. Путь от A до B занимает 3 часа 24 минуты, а от B до A - 3 часа 42 минуты. Если длина подъема составляет 12 км, найдите длину горизонтального и нисходящего участков дороги от А до Б.
Формула движения: S=v*t
S - расстояние v - скорость t – время
х - путь на горизонтальном участке.
у - путь нисходящий (на спуске) от А до Б и на подъёме от Б до А.
3 часа 24 минуты = 3,4 часа.
3 часа 42 минуты = 3,7 часа.
Примечание:
путь, который по дороге от А до Б был спуском, по дороге от Б до А становится подъёмом, горизонтальный без изменений.
Обозначения:
х/10 - время на горизонтальном участке туда и обратно.
у/15 - время на спуске от А до Б.
у/6 - время на подъёме от Б до А.
12 : 6 = 2 (часа) - время на подъёме от А до Б.
12 : 15 = 0,8 (часа) - время на спуске от Б до А.
По условию задачи система уравнений:
х/10 + у/15 + 2 = 3,4
х/10 + у/6 + 0,8 = 3,7
Умножить оба уравнения на 30, чтобы избавиться от дроби:
3х + 2у + 60 = 102
3х + 5у + 24 = 111
3х + 2у = 42
3х + 5у = 87
Умножить любое из уравнений на -1, чтобы применить метод сложения:
3х + 2у = 42
-3х - 5у = -87
Сложить уравнения:
3х - 3х + 2у - 5у = 42 - 87
-3у = - 45
у = -45/-3
у = 15 (км) - путь нисходящий (на спуске) от А до Б и на подъёме от Б до А.
Теперь подставить значение у в любое из двух уравнений системы и вычислить х:
3х + 2у = 42
3х = 42 - 2у
3х = 42 - 2*15
3х = 12
х = 4 (км) - путь на горизонтальном участке туда и обратно.
b) My friend wasn't waiting for me when I arrived late. 7.a) When did he have the accident? -As he was climbing up the ladder. b) When was he having the accident? -As he was climbing up the ladder. 8.a) l read a book when she sent me an SMS. b) l was reading a book when she sent me am SMS. 9.a) Did you eеat lunch when the fire alarm rang? b) Were you eating luncn when the fire alarm rang. 10.a) lt was a beautiful day The sun shone and there wasn't a cloud in the sky. b) lt was a beautiful day. The sun was shining and there wasn't a cloud in the sky.
Look at the of sentences below. Both of them are grammatically correct. Choose one sentence in each pair, a or b, that is more logical. 1.a) lt rained heavily when I ran for the bus. B) lt was raining heavily when I ran for the bus. 2.a) The rain jjust came into the station when we arrived on the platform. b) The train was just coming into the station when we arrived on the platform. 3.a) He broke his leg while riding his bike at the weekend. b) He was breaking his leg while riding his bike at the weekend. 4.a) While I was watching TV, someone knocked on the window. bjWhile I was watching TV, someone was knocked on the window. 5 a) No wonder she fell off her bike. She didnt Innk here che iwac in
6 Complete the sentences with when or while. 1) The boys were playing football ... the ball flew into the window. 2) Ronny was painting the fence ... the bucket of paint turned over. 3) Denny was putting a tent ... the girls were gathering wood for fire. 4) Rita was sleeping .. the alarm- rang. 5) Nelly was peeling potatоes her sister was cutting chicken into pieces. 6) Nigel was skiing he fell down and broke his leg. 7) They were arguing ... Mrs Elliot entered the room. 8) ... my mother was watching her favorite show on TV, father making coffee. 9) She was tying a letter some mistakes. 10) They were driving towards the village it started clock she found to snow.
В решении.
Объяснение:
Велосипедист движется по дороге эта дорога состоит из горизонтальных, восходящих и нисходящих участков. Скорость велосипедиста составляет 10 км/ч по горизонтальной дороге, 6 км/ч по дороге в гору и 15 км/ч на спуске. Путь от A до B занимает 3 часа 24 минуты, а от B до A - 3 часа 42 минуты. Если длина подъема составляет 12 км, найдите длину горизонтального и нисходящего участков дороги от А до Б.
Формула движения: S=v*t
S - расстояние v - скорость t – время
х - путь на горизонтальном участке.
у - путь нисходящий (на спуске) от А до Б и на подъёме от Б до А.
3 часа 24 минуты = 3,4 часа.
3 часа 42 минуты = 3,7 часа.
Примечание:
путь, который по дороге от А до Б был спуском, по дороге от Б до А становится подъёмом, горизонтальный без изменений.
Обозначения:
х/10 - время на горизонтальном участке туда и обратно.
у/15 - время на спуске от А до Б.
у/6 - время на подъёме от Б до А.
12 : 6 = 2 (часа) - время на подъёме от А до Б.
12 : 15 = 0,8 (часа) - время на спуске от Б до А.
По условию задачи система уравнений:
х/10 + у/15 + 2 = 3,4
х/10 + у/6 + 0,8 = 3,7
Умножить оба уравнения на 30, чтобы избавиться от дроби:
3х + 2у + 60 = 102
3х + 5у + 24 = 111
3х + 2у = 42
3х + 5у = 87
Умножить любое из уравнений на -1, чтобы применить метод сложения:
3х + 2у = 42
-3х - 5у = -87
Сложить уравнения:
3х - 3х + 2у - 5у = 42 - 87
-3у = - 45
у = -45/-3
у = 15 (км) - путь нисходящий (на спуске) от А до Б и на подъёме от Б до А.
Теперь подставить значение у в любое из двух уравнений системы и вычислить х:
3х + 2у = 42
3х = 42 - 2у
3х = 42 - 2*15
3х = 12
х = 4 (км) - путь на горизонтальном участке туда и обратно.
Проверка:
4/10 + 15/15 + 12/6 = (12 + 30 + 60)/30 = 102/30 = 3,4 (часа), верно.
4/10 + 15/6 + 12/15 = (12 + 75 + 24)/30 = 111/30 = 3,7 (часа), верно.