The workers demanded that their employer_____ their working conditions.
Team leaders must ensure that all members ______ their natural desire to avoid the embarrassment associated with making mistakes.
With inspiration from other food cultures, American food culture can take a ______ for the better.
Carbon dioxide, which makes a ______ between us and the sun, prevents heat from getting out of the atmosphere easily, so the earth is becoming warmer.
In much of the animal world, night is the time ______ for sleep—pure and simple.
Butterflies ______ a sweet liquid produced by flowers, which bees and other insects collect.