dīng shì dīng , mǎo shì mǎo
lit. a nail is a nail and a rivet is a rivet (idiom)
fig. meticulous; conscientious; unambiguous
钉
dīng
nail
是
shì
to be (followed by substantives only)
,
,
铆
mǎo
to fasten with a rivet; to rivet