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