PTE

to treat food so that it remains usable for longer without spoiling

naturally replenished on a timescale relevant to human use, as with sunlight, wind, or growing biological resources

able to continue over time without exhausting resources or seriously damaging the natural systems on which it depends

capable of poisoning or causing harmful biological effects in living things

a shortage of sufficient usable or accessible water to meet the needs of people or the environment

an unplanned fire that burns through vegetation in a natural or partly natural area

connected with the locations, physical features, or spatial relationships of places on Earth

toward or within the interior of a country or region, away from the coast

relating to a particular area within a country or a larger part of the world

a scientist who studies objects in space and the universe

the scientific study of objects in space and the universe

to move along a path around another body or a shared center under gravity

a natural or artificial object that moves in orbit around a larger body

to exert a force that tends to draw another object closer

a real or imaginary line about which an object rotates

able to remain useful for a long time by resisting wear or damage

a reflected sound heard again after the original sound

able to bend easily without breaking

the gravitational interaction through which physical bodies attract one another

an optical component that redirects light by refraction to form images or change a beam

the rate at which energy is transferred or work is done

to send incident light back from a surface rather than let all of it pass through

to turn around an axis, or cause something to turn in this way

allowing light to pass through so that objects beyond can be seen clearly

to move repeatedly back and forth, usually over a small distance, or cause something to do this

a type of material considered in terms of its physical or chemical properties

a medicine that kills bacteria or stops their growth and is used against certain bacterial infections

lasting for a long time or repeatedly returning, especially when describing a health condition

a mental health condition involving persistent low mood or loss of interest and other changes that can impair daily functioning