You can refer to a situation as quicksand when you want to suggest that it is dangerous or difficult to escape from, or does not provide a strong basis for what you are doing.
例句
I was about to sink into the quicksand of sin...我就要陷入罪孽的深淵了。The research seemed founded on quicksand.這項研究猶如建在流沙之上，基礎(chǔ)極不穩(wěn)固。
英英詞典釋義
Noun
1. a treacherous situation that tends to entrap and destroy
2. a pit filled with loose wet sand into which objects are sucked down