Задание 1 By the time Alexander was twenty he (become) a professional scientist.
Задание 2
When Alex (hang up) the phone he (realise) he (forget) to
take down the caller’s name and number.
Задание 3
He (work) in the laboratory for three hours when he stopped for a break.
Задание 4
Alex (read) a book all night and was very sleepy the next morning.
Задание 5
They were exhausted because they (play) chess all day.
Задание 6
Before Fleming invented penicillin, he (experiment) with bacteria for a long
time.
Задание 7
I (decide) that I was going to study Chemistry before I finished secondary
school.
Задание 8
Alexander (already/learn) to read and write before he started school.
Задание 9
He was upset because he (miss) the last train.
Задание 10
He (reach) his house by the time it started to rain
became, hanged up, realized, forgot, works, has been read, plays, had experiment, decided, learned, missed, reached