metal / mettle
The substance versus courage.
Metal is the substance: a metal bar. Mettle is courage or spirit: test their mettle. Do not write test their metal.
Examples
Use a metal bar
Use test their mettle
Avoid test their metal
The substance versus courage.
Metal is the substance: a metal bar. Mettle is courage or spirit: test their mettle. Do not write test their metal.
Use a metal bar
Use test their mettle
Avoid test their metal