Rewrite each original sentence in order to make it easier to understand by non-native speakers of English. You can do so by replacing complex words with simpler synonyms (i.e. paraphrasing), deleting unimportant information (i.e. compression), and/or splitting a long complex sentence into several simpler ones. The final simplified sentences need to be grammatical, fluent, and retain the main ideas of their original counterparts without altering their meanings.

The Sahara Pump Theory is a hypothesis that explains how flora and fauna left Africa to penetrate the Middle East and then Europe and Asia.
The Sahara Pump Theory is a hypothesis that explains how the flora and fauna left Africa to spread to the Middle East and then to Europe and Asia.

Many specialize in machine construction, medical equipment, international trade, optics and electronics.
Specialties are machine construction, medical equipment, international trade, optics and electronics.

It debuted at # 20 on VH1's VH1 Top 20 Video Countdown on June 28, 2008.

It started out as #20 on the Top 20 countdown on VH1.  It debuted there on June 28, 2008.

