to take out; to produce; to pick out; to fetch; to retrieve
subject; theme; homework; assignment; problem (that needs solving); task
to grapple with; to wrestle with; to engage in a bout; to tackle (e.g. a problem); to come to grips with; to work hard on
material; substance; matter
energy; energy; strength; energy source; energy resource; food energy
ultrahigh temperature; superhigh temperature; extreme heat
vacuum; absolute void; complete vacuity
flight time; number of flight hours
light (i.e. not heavy); feeling light (i.e. offering little resistance, moving easily); light (i.e. of foot); effortless; non-serious; minor; slight
to be broken; to break; to break (down); to stop working; to fall through (of a plan, deal, etc.); to collapse
powder; finely crushed substance; fines
to mix; to blend; to combine
to pile up; to heap up; to stack up; to repeat many times over; to go through repeatedly; to accumulate
to be mixed; to be blended with; to associate with; to mingle with; to join
vaporization; vaporisation; evaporation
finally; after; following; at the end (of)
to mix; to stir; to blend
clear; obvious; evident; bright; light
hasty; impatient; restless; rash
character (of a person); personality; disposition; characteristics; nature (of a thing, event, etc.)
detection; sense (e.g. sensor)
withdrawal; secession; elimination; desorption
specialist; expert; professional; authority; pundit
outsider; layman; amateur
to permit; to allow; to forgive; to pardon; to exempt (someone) from; to remit; to acknowledge
carefree; comfortable; at ease; easygoing; happy-go-lucky
to wield; to brandish; to display (one's knowledge); to show off; to abuse (one's power); to manipulate someone
sample; specimen; test piece
unfortunately; regrettably
there is no need to ...; never happens; there is never a time when