i am not sure what you mean. but i can make some examples for "me ,my and 了 ，是". 

acutally , you must know the difference between ME and MY. So i will not say any thing about them.

"了"， it means you have done something, it has/had be finished. for example: i had/has finished my homework .(我已经完成我的家庭作业了). please pay attention to the action is finished. 

"是"， i am a student.(我是一个学生)， it is equivalent to “be（am, is and are）”

i hope it will be hlpeful for you.

   i dont know why you have difficulties to distinguish 了 and 是，i think 是 is better to understand,so i explain it firstly,是 means 'be（am,are,is was ,were and other form of be）'  ,for example,i'm a student.in chiense,it's 我是学生。我means i ,是 means am,是 means student.you're my friend.means 你是我的朋友。你 means you,是 means are,我的means my,朋友 means friend.she is a teacher.means 她是一个老师。she means 她，是 means is,一个 means a ,老师 means teacher.i hope you will get this point.i want you to make a translation if you dont mind:they are teachers.('they' in chinese is 他们,)

while 了,it has several meanings,one of the most important uses is to stand the past tense,for example,i passed the Chinese exam.我通过了汉语考试。我 means i,通过了 means passed,the chinese exam means 汉语考试..通过 is a verb in here,it means pass,while 通过了 is the past tense,means passed.

我懂英文，可没看懂你写的。

Me 是宾格的“我”,如：你告诉“我”。

My是所属格，表“我的”，如：“我的”书。

“了”一般表示过去或表示完成的时态，如：我看了这本书。

“是”就是“be” 如：他们是学生。

如果我懂英文，就好了。勉强。

谢谢你们。 Thank you guys very much for your time and explanation. (When I talked about "Me" and "My" "relationship" with 是， and 了） I was referring  the time that have taken me to understand them (是 and 了). Again thanks a lot.