Correct

屡试不爽

/ lǚ shì bùshuǎng /
Strokes

Definition

well-tried/time-tested

Example

Definition

be put to repeated tests and proved right/satisfactory; be proved effective every time it is used; stand/pass many tests

1
de
fāngàn
方案
shìshuǎng
屡试不爽
  
,
yīnggāi
应该
cǎi
采纳
  

His plan should be adopted for it has proved quite effective after repeated tests and trials.

2
shìshuǎng
屡试不爽
de
bàn
办法

time-tested method