Having been used for a long time, a indistinctive symbol will gain "secondary meaning" and become distinctive.

商标必须具有显著性，但一个不具有显著性的标记在长期使用后会形成“第二含义”而获得显著性。

Bluish green light flashed six to seven times like lightening bolts, and there indistinctive sounds like drumbeats; soon, an earthquake struck.

见碧光闪烁，如电者六七次，隐隐有声如雷鼓，巳而地震。