Réponse :

1.a. How books are made

2.b. First of all, big sheets of paper are printed.

3.a. Each sheet contains the text of a number of pages.

4.b. The sheets are folded and cut to produce sections of the book

5.a. These sections are called signatures.

6.b. All the signatures are put together in the correct order  

7.a. Then they are bound together and their edges are trimmed

8.b. The cover - which was printed separately - is attached

9.b. Now the book can be published

Explications :