(a) Pasteur was a famous scientist. (Interrogative) He discovered that many diseases are caused by germs. (b) He found cures for several of them. (Negative) (c) At first he had treated only animals. (Future Indefinite) (d) He found a mad dog and injected some germs of the diseases into its blood. (Interrogative) The dog was cured. (e) It was a very important invention in the world of medical science. (Exclamatory)