snake的基本意思是“蛇”,喻指“冷酷阴险的人”“虚伪的人”“卑鄙的人”。

a snake in the grass
伪装成朋友的阴险的人 deceitful or treacherous person who pretends to be a friend
I won't trust that snake in the grass. 我不相信那个奸诈的人。
That snake in the grass reported me to the boss.那个口蜜腹剑的家伙到老板那里告了我一状。
Don't be deceived by their friendliness—the two old ones may be trustworthy, but the younger brother is a real snake in the grass.不要被他们的友善蒙住眼睛——两个哥哥或许还值得信任,但那弟弟实际上很阴险。

He was bitten by a poisonous snake.他被毒蛇咬了。
The snake's bite is sometimes poisonous.蛇的唾液往往有毒。
Not all snakes are poisonous.并非所有的蛇都有毒。
In Africa the snake is still sacred with many tribes.非洲许多部落仍然把蛇奉为神物。
The bite of the poisonous snake on his shoulder is the fatal wound.毒蛇在他肩上咬的一口是致命的伤。
Mother and daughter were alike in their fear of snakes.母女俩同样怕蛇。
The place is full of insects, to say nothing of the snakes.这地方到处是虫子,更不用说蛇了。
Some snakes are poisonous.有些蛇是有毒的。
Snakes crawl.蛇会爬行。

snake还可用作动词,表示“蛇行斗折”或“弯弯曲曲地移动〔前进〕”。例如:
The train snaked through the mountains.火车在山区蜿蜒地向前行驶。
The river snaked away into the distance.那条河蜿蜒曲折地流向远方。

［词源］  ＜古英语snaca(爬行,蠕动)