User-agent: Googlebot
Allow: /
Disallow: /?*s=*
Disallow: /?*a=*

User-agent: msnbot
Allow: /
Disallow: /?*s=*
Disallow: /?*a=*
Crawl-delay: 1

User-agent: Yandex
Allow: /
Disallow: /?*s=*
Disallow: /?*a=*
Crawl-delay: 1

User-agent: Baiduspider
Allow: /
Disallow: /?*s=*
Disallow: /?*a=*
Crawl-delay: 1

User-agent: *
Disallow: /