instruction:
In this task, we ask you to elaborate the sentence without changing its general meaning. You can do so by explaining further the input sentence, using more precise wording, adding qualifiers and auxiliary information etc.
question:
The atomic radius of an element is the distance between the nucleus and the edge of the electron cloud .
answer:
The atomic radius of a chemical element is a measure of the size of its atoms , usually the mean or typical distance from the center of the nucleus to the boundary of the surrounding shells of electrons .


question:
Haeckel promoted and popularised Charles Darwin 's work in Germany and developed the controversial recapitulation theory ( " ontogeny recapitulates phylogeny " ) .
answer:
Haeckel promoted and popularised Charles Darwin 's work in Germany and developed the influential but no longer widely held recapitulation theory ( " ontogeny recapitulates phylogeny " ) claiming that an individual organism 's biological development , or ontogeny , parallels and summarises its species ' evolutionary development , or phylogeny .


question:
Self-driving cars could take people where they wanted to go at a lower cost than a taxi or ridesharer .
answer:

Autonomous vehicles could allow the public to use roads in low cost-per-kilometre , self-navigating vehicles to a preferred destination at a significantly lower cost than current taxi and ridesharing prices .