To say "my arm is injured" in English, you can say "may ahm iz in-jurd." The emphasis should be on the first syllable of "arm" and "injured." Be sure to pronounce the "r" sound in "arm" and the "d" sound in "injured." If you need to ask for medical assistance, you can say "I need a doctor, my arm is injured." This can be translated as "ay need a dawk-ter, may ahm iz in-jurd."
