Are these sentences correct?
b) He told me about many cities he had visited during his travelling.
c) I couldn’t answer teacher`s questions because I hadn’t revised anything before the exam.
d) When we came to the theater,the play had already started.
e) I went to watch TV after I had written a letter to my friend.
f) She couldn’t find a book I had lent her.
g) She told me that she had worked in France and Germany.
h) When I came to the car parking I realized that I had lost the keys.
i) It was a firm I had never heard before,
j) My headache disappeared after I had taken medicine.

Are these sentences correct? I doubt about using Past perfect correctly here.

Question

Are these sentences correct?
b)	He told me about many cities he had visited during his travelling.
c)	I couldn’t answer teacher`s questions because I hadn’t revised anything before the exam.
d)	When we came to the theater,the play had already started.
e)	I went to watch TV after I had written a letter to my friend.
f) She couldn’t find a book I had lent her.
g)	She told me that she had worked in France and Germany.
h)	When I came to the car parking I realized that I had lost the keys.
i)	It was a firm I had never heard before,
j)	My headache disappeared after I had taken medicine.

Are these sentences correct? I doubt about using Past perfect correctly here.

Answer

b)	He told me about the many cities that he had visited during his travels.
c)	I couldn’t answer the teacher's questions because I hadn’t revised before the exam.
d)	When we arrived at the theatre, the play had already started.
e)	I went to watch TV after I had written a letter to my friend.
f) 	She couldn’t find the book that I had lent her.
g)	She told me that she had worked in France and Germany.
h)	When I arrived at the car park, I realized that I had lost my keys.
i)	It was a firm that I had never heard of before.
j)	My headache disappeared after taking medicine.