If something or someone is obscure, they are unknown, or are known by only a few people.
obscure explicit 隐晦的
Obscured property 遮挡物
I found her lecture very obscure.
The view was obscured by fog.
A random sample or method is one in which all the people or things involved have an equal chance of being chosen.
Randomly vigorously 瞎起劲
randomly fluctuating 随机起伏
chosen randomly 随机选择
The winning numbers are randomly selected by computer.
My phone seems to switch itself off randomly.
An altar is a holy table in a church or temple.
altar boy 祭台助手
altar candles 神坛蜡烛
altar table 祭坛桌
high altar 祭坛
The altar was flanked by two Christmas trees
On the altar, he had set up posters, candles, and songbooks.