1. The books are being bought by Sara. - Present Continuous Passive
2. The books have been bought by Sara. - Present Perfect Passive
3. The books were bought by Sara. - Past Simple Passive
4. The books had been bought by Sara. - Past Perfect Passive
5. The books were being bought by Sara. Past Continuous Passive
6. The books will be bought by Sara. - Future Simple Passive
7. The books will have been bought by Sara. - Future Perfect Passive