He __________ knocked the glass off the table just for fun.

Cheetahs are considered an __________ species, facing a high risk of extinction in the wild. Their global population is estimated to be fewer than 7,000 mature individuals and continues to decrease.

What's this?

The disappearance of an insect or a frog may not seem very important, but every animal is an important __________ in nature.

When you're writing to apply for a job, please use __________ language.

Only after I __________ this math problem can I start to solve it.

n. 水族馆

Polar bears are losing their __________ as ice is melting at a shocking rate.

v. 促使，引起