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В треугольнике АВС угол С равен 90°, cos A=2√2/3, BC=2. Найдите AB.

Переведите  1, 3, 4 абзацы.

The Tower of London

1. The Tower of London was begun by William the Conqueror as a fortress and palace. Later kings made it larger and stronger and kept soldiers, armour, weapons, treasure,and sometimes  important prisoners there. For five hundred years coins of realm were minted at the Tower and official documents stored in some of the castle buildings. There was  ever  a zoo there, which began as the king's private collection of animals.

2. Nowadays it is busy with thousands of visitors. In fact the Tower  today is like a traditional English village. The ravens are certainly among the the most important residents in Tower, for — so the story goes — if they every leave, the Tower will fall and England with it.

З. These days there are usually about six ravens hopping and necking around the Tower lawns in the daytime. One of the Yeoman Warders cares for,them. He feeds them on raw meat, biscuits soaked in blood, rabbits' heads, fruit and eggs. He talks them back into their cage every night, and from time to time clips their wings — just to take sure that they never do leave.

4. The Yeoman Warders have guarded the Tower since reign of Henry VIII. Every day at the Tower ends with the Ceremony of the Keys. The soldiers of the Tower Guard escort the Chief Yeoman Warder as he looks the outer gates. When this is done the guard salute "the Queen's keys" and the Chief Warder calls out "God preserves Queen Elizabeth". Then he takes the keys to the Governor in Queen's House. The Tower of London is safe and secure for the night. It is a very old ceremony —700 years old.

VII. Прочитайте 2 абзац и вопрос к нему. Из приведенных вариантов ответа укажите номер предложения, содержащего правильный ответ на поставленный вопрос.

Why are the ravens cared to carefully in the Tower?

1. These days there are usually about six ravens hopping and necking around the Tower lawns in the daytime.

2. Nowadays it is busy with thousands of visitors.

З. The ravens are certainly among the most important residents in the Tower, for — so the story goes — if they every leave, the Tower will fall and England with it.

1. По 5 электронов на внешнем электронном слое находится в атоме каждого из химических элементов:

1) Ве, В, Li

2) As, Se, Br

3) C, Si, Al

4) N, P, As

Ответ 4, но можете объяснить, почему?) 

2. Ковалентная неполярная связь имеется в

1) молекуле воды

2) кристалле SiO2

3) кристалле кремния 

4) молекуле пероксида водорода

Ответ 3, но можете объяснить, почему?) 

3. Положительныую степень окисления атом кислорода имеет в соединении

1) H2O

2) H2O2

3) F2O

4) Fe3O4

Ответ 3, но можете объяснить, почему?)

4. К кислотным, и, соответственно, основным оксидам относятся:

1) CO и Na2O

2) CO2 и MgO

3) Al2O3 и P2O5 

4) SO3 и ZnO

Ответ 2, но можете объяснить, почему?)

5. Гидроксид кальция реагирует с

1) углекислым газом

2) кислородом

3) водородом

4)  поваренной солью 

Ответ 2, но можете объяснить, почему?)