拯救山地大猩猩的努力显示出进步的迹象

hum – n. a low continuous sound

chill – adj. informal : relaxed

poaching – n. the act of hunting or fish illegally

critically – adv. medical relating to or involving great danger of death

vulnerable –adj. able to be harmed, at risk

monitor – v. to watch, observe, listen to, or check (something) for a special purpose over a period of time

reunite – v. to bring (people or things) together again especially after they have been apart for a long time

regulate – v. to control or supervise something

submissive – adj. willing to obey someone else