If the premise and the conclusion in two different statement are the same, but their relative positions in the argument are different, they are still the same logical statement.
I love you very much because you have a beautiful mind. B --> L Since you have a beautiful ming, I love you to the bone. B --> L
LZ, you confused the definition of necessary condition and sufficient condition.
(1)我GMAT考了高,因为我英语好 (2)我英语好,所以我GMAT考了高
In both statement, the sufficient condition is My English is good; and the necessary condition is My GMAT score is high. Because leads a sufficient condition; therefore leads a necessary condition.
If you want to say 即英语好是GMAT考了高的必要条件, then you should claim: Since my GMAT score is high, my English is superb. This is different from the following statement: Since my English is superb, my GMAT score is high.