Mixed Prepositions Exercise 17

Complete the text below by choosing the correct prepositions, then press "Check" to check your answers.
Orchids are the largest and most diverse the flowering plant families, with over 800 described genera and 25,000 species. Some sources give 30,000 species, but the exact number is unknown since classification differs greatly the academic world. Revisions of different genera occur a monthly basis and this will increase the growing use genetic research and biochemistry. More than 100,000 hybrids and cultivars, produced horticulturists, have been created the introduction of tropical species the 19th century. The Kew "World Checklist of Orchids" includes about 24,000 accepted species. About 800 new species are added each year. Orchids, along grasses, are considered examples the most advanced (derived) floral evolution through their interactions pollinators and their symbiosis orchid mycorrhizal fungi.

Source: http://en.wikipedia.org/wiki/Orchids
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