The Chinese idiom **力所能及** is formed through a parallel and complementary four-character structure common in classical Chinese, where **力** (power/ability) and **所** (that which) combine to mean "that which one's strength encompasses," while **能** (can) and **及** (reach/attain) combine to mean "is able to reach"; the two parallel phrases **力所** and **能及** are placed side-by-side to reinforce and synonymously emphasize the single concept of "within the scope of what one's power can achieve" or simply "within one's capability."