Hxen.com's tips：Every day persisted can learn English well!-->■Learn English Everyday■
steep – adj. dropping or falling sharply; extremely high
microbial – adj. of or relating to microbes or bacteria
cliff – n. a high, steep surface of rock, earth, or ice
degree – n. a form of measurement for the size of angles, the shape formed by two lines extending from the same point
slope – n. ground that slowly drops downward or upward; ground that slopes
volume – n. an amount of something
cryptic – adj. difficult to understand; having or seeming to have a hidden meaning
