Use the pronouns "some, any, no" and their derivatives "somebody, anybody, nobody, something, anything, nothing".
1. There are .... apple-trees in the garden. 2. Has he ... money in his pocket? 3. I see ... in the dark room. 4. He had ..... in his hand. 5. Can .... solve this difficult problem on the computer? 6. Listen, ...... is knocking at the door. 7. Are there ... lectures in the evening?. 8. Ask ... else about it. 9. I must tell you .... very interesting. 10. I don't know .... about this man.

в предложении под номером 10 не может стоять nothing, т.к. предложение уже отрицательное. В английсклм предложении только ОДНО отрицание!!!