Focus on the pronunciation of strength
English definition of “strength”
/streŋkθ/, /streŋθ/ n [U] (PHYSICAL POWER)
› the ability to do things that demand physical effort, or the degree to which something is strong or powerful: After having surgery, it takes a while to get your strength back. Making baskets requires skill more than physical strength. The storm is gathering/gaining strength. › The strength of a drug is its ability to have an effect.