Here are the correct answers along with their translations:
They didn’t go for a walk because it was raining.
b) was raining
Они не пошли на прогулку, потому что шёл дождь.I didn’t know who that woman was. I had never seen her before.
c) had never seen
Я не знал, кто была та женщина. Я никогда её не видел раньше.It was very noisy next door. Our neighbours were having a party.
b) were having
Соседи Next door было очень шумно. Наши соседи устраивали вечеринку.We were not hungry. We had just had lunch.
c) had just had
Мы не были голодны. Мы только что пообедали.We enjoyed the concert last night very much.
a) enjoyed
Нам очень понравился концерт прошлой ночью.He broke his leg while he was playing tennis.
b) was playing
Он сломал ногу, пока играл в теннис.I met Mary in the supermarket yesterday.
a) met
Я встретил Мэри в супермаркете вчера.I apologized because I had forgotten his book.
c) had forgotten
Я извинился, потому что забыл его книгу.He came home at 7 o'clock yesterday.
a) came
Он пришёл домой в 7 часов вчера.I first met him when we were studying in Oxford.
b) were studying
Я впервые встретил его, когда мы учились в Оксфорде.Yesterday I had done my homework by 6 o'clock.
c) had done
Вчера к 6 часам я сделал свою домашнюю работу.When the teacher came into the classroom, the children were running around.
b) were running
Когда учитель вошёл в класс, дети бегали вокруг.When I came home, I realized I had lost the keys.
c) had lost
Когда я пришёл домой, я понял, что потерял ключи.He told me that Jane was going shopping.
b) was going
Он сказал мне, что Джейн шла за покупками.I was reading a book the whole evening yesterday.
b) was reading
Я всю прошлую вечер читал книгу.When I met John, he was going to the railway station.
b) was going
Когда я встретил Джона, он шёл на вокзал.They went to the Tretyakov Gallery last week.
a) went
Они ходили в Третьяковскую галерею на прошлой неделе.She returned the book which she had taken the day before.
c) had taken
Она вернула книгу, которую взяла накануне.While my friend was fishing, I watched the birds.
a) watched
Пока мой друг ловил рыбу, я наблюдал за птицами.We asked him how many places of interest he had already seen.
c) had already seen
Мы спросили его, сколько интересных мест он уже видел.
Feel free to ask if you need further explanations on any specific choice!