About pronunciation of /r/ & /l/

Actually it was my first time to record and listen to my voice. Differentiation between /r/ and /l/ is somewhat easy in a word but when it comes to sentence, it gets more difficult to pronounce. I need to practice reading sentences to be fluent. Through this audio clip, I figured that I can't identify pronunciation of  /z/&/dg/ and /i:/&/i/. There are many problems in my pronunciation besides those what I mentioned above. Anyway it was a good chance for me to observe my pronunciation objectively. I hope much improvement in my pronunciation through this subject.