Demonstrative pronouns.
Examples
Voici mes livres et ceux de Jean. Here are my books and John's.
Voici mes plumes et celles que vous avez achetées. Here are my pens and those that you bought.
J'ai deux montres. Aimez-vous celle-ci ou celle-là? I have two watches. Do you like this one or that one?
Lamartine et Balzac. Celui-ci est un grand romancier; celui-là un grand poète. Lamartine and Balzac. The former is a great poet, the latter a great novelist.
C'est mon ami.--Ce sont eux.--C'est moi.--C'est un poète.--C'est difficile, etc. He (it) is my friend.--It is they.--It is I.--He is a poet.-It is difficult, etc.
Ceci est le mien, cela est le vôtre. This (indefinite) is mine, that is yours.
A. 1. Do you see my dogs? These are greyhounds, those are dachshunde. 2. They[1] are good dogs. 3. I hear a[2] noise; it[1] is burglars. 4. It was a burglar, but it[3] seemed to me a little late to go down. 5. I want to learn that one[4] of the sciences which is most difficult. 6. These soldiers are better fed than those of Napoleon. 7. That makes no difference.[5] 8. That's all right but look at this! 9. It[3] would be difficult to imitate the grunt of a pig. 10. No, on the contrary, it[1] would be easy. 11. That[1] is what he said. 12. Was[6] it you who neglected this affair? 13. It was[6] we who did it. 14. I saw an officer and a grenadier; the former was better dressed than the latter. 15. Those who wish to be educated in this school must pay double what those pay who are educated elsewher. 16. The hardest thing[4] is[7] to learn to[8] keep still. 17. What I ought to do is[7] to learn all that[9] I can. 18. Let[4] my soldiers be[10] well dressed and well fed.
[Footnotes 1: what pronoun? 2: du. 3: il. 4: omit. 5: rien. 6: present tense. 7: c'est. 8: à. 9: ce que. 10: why subjunctive?]