Question

sort the words according to the meanings of their shared roots. subjugate cardiologist submerge substandard subterranean echocardiogram heart below

Explanation:

The root "cardi -" relates to the heart, seen in "cardiologist" (a doctor specializing in heart - related issues) and "echocardiogram" (a test of the heart). The prefix "sub -" means below, as in "subjugate" (bring under control), "submerge" (go below the surface), "substandard" (below standard), and "subterranean" (below the earth).

Answer:

heart: cardiologist, echocardiogram
below: subjugate, submerge, substandard, subterranean