Tongue positioning for だ、な、ら are very similar that they sound alike. The key is to enunciate the first consonant sound. だ(da) pushing your tongue behind the upper front teeth, strong “d” sound. な(na) holding your tongue flat press on the upper part of mouth, release air through the nose. ら(ra) curling your tongue, gently brush the upper part of your mouth.
Watch and follow the tongue position animation for clarification.
entering school/study abroad