Ответ:
2. If I call him, will he answer?
3. We will be late if we do not leave now.
4. If you learn the piano, will you play ...?
5. She will be good if she practises.
6. If he does not buy the guitar..., they will sell it.
Объяснение:
Образование:
If + Present Simple (придаточная часть), Future Simple (главная часть).
Present Simple - подл. + глагол (если he, she, it, то глагол + окончание s).
Future Simple - подл. + will + глагол