Нужна помощь в решение задания по английскому

Вопрос 1
Текст вопроса
By the end of the World War II the ball-point pens (to become) very popular all over the world.

Выберите один ответ:
a. had become
b. became

Вопрос 2
Текст вопроса
By 1927 Baird (to send) pictures from London to Glasgow.

Выберите один ответ:
a. sent
b. had sent

Вопрос 3
Текст вопроса
A Scotsman, Baird, (to transmit) the first TV picture in 1825.

Выберите один ответ:
a. had transmitted
b. transmitted

Вопрос 4
Текст вопроса
I looked at the old man and (to understand) that he (to know) I (to sit) on the bench because of him.

Выберите один ответ:
a. had understood, had known, sat
b. understood, knew, had sat

Вопрос 5
Текст вопроса
Yesterday Mrs Clinton (to see) a beautiful woolen dress in a shop.

Выберите один ответ:
a. had seen
b. saw

Вопрос 6
Текст вопроса
When she (to return) home after her shopping, her husband was glad to see her.

Выберите один ответ:
a. returned
b. had returned

Вопрос 7
Текст вопроса
He (to think) that he never (to see) such a good book.

Выберите один ответ:
a. thought, had ...seen
b. thinks, was ...seeing

Вопрос 8
Текст вопроса
Two minutes ago the horse (to stop) suddenly.

Выберите один ответ:
a. had stopped
b. stopped

Вопрос 9
Текст вопроса
The man (to feel) that something (to frighten) the horse.

Выберите один ответ:
a. felt, had frightened
b. feels, has frightened

Вопрос 10
Текст вопроса
Yesterday the dog (to see) a wolf and (to disappear) with it in the forest.

Выберите один ответ:
a. has seen, has disappeared
b. saw, disappeared

Вопрос 11
Текст вопроса
I (to see) him a month ago, when he just (leave) his job with the big firm.

Выберите один ответ:
a. saw, had ...left
b. had seen, left

Вопрос 12
Текст вопроса
By that time the workers (to built) already a 25-storey house.

Выберите один ответ:
a. had ...built
b. built

Вопрос 13
Текст вопроса
Jack said that he (to read) already this magazine.

Выберите один ответ:
a. read
b. had ...read

Вопрос 14
Текст вопроса
He already (to know) the news before the meeting (to begin).

Выберите один ответ:
a. had ...known, began
b. has ...known, begins

Вопрос 15
Текст вопроса
The lecturer already (to explain) the new grammar rules many times before.

Выберите один ответ:
a. explained
b. had ...explained

Вопрос 16
Текст вопроса
The foreign tourists (to see) many places of interest before they (to leave) London.

Выберите один ответ:
a. had seen, leave
b. had seen, left

Вопрос 17
Текст вопроса
She (to see) her native house after they (to have) dinner at a restaurant.

Выберите один ответ:
a. saw, had had
b. see, had

Вопрос 18
Текст вопроса
He (to stay) in bed for a week after he (to catch) cold.

Выберите один ответ:
a. stayed, has caught
b. stayed, had caught

Вопрос 19
Текст вопроса
My sister (not to see) all the places of interest before she (to leave) the city.

Выберите один ответ:
a. had not seen, left
b. had not seen, leaves

Вопрос 20
Текст вопроса
The outstanding boxer (to give) a big party after he (to break) a world record.

Выберите один ответ:
a. gives, has broken
b. gave, had broken