Planets have been studied by scientists for centuries.
Meaning: This sentence tells us that scientists have been studying planets for a very long time.
Choice of Words: "Scientists" are people who study science. "Centuries" means a long period of time, typically 100 years.
Alternative Expressions
Planets are studied by scientists who have been doing so for centuries.
Meaning: This sentence means that people who study the natural world have been learning about planets for a very long time.
Choice of Words:Planets are large, round objects that orbit the sun. Scientists are people who study the natural world. Studied means to examine and learn about something. Centuries are long periods of time, each lasting 100 years.
Scientists have studied planets for hundreds of years.
Meaning: This sentence means that people who study the natural world have been learning about planets for a very long time.
Choice of Words:Planets are large, round objects that orbit the sun. Scientists are people who study the natural world. Studied means to examine and learn about something. Centuries are long periods of time, each lasting 100 years.