非常感谢来自外国朋友h2h2的私信回复，我把他给我的回答详细po在这里，和大家一起学习

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h2h2:

Total Assets=TA, Total Liabilities=TL, Total Equity=TE, Return=R, Return On Assets=ROA, Return On Equity=ROE, Assets To Equity=ATE.

1. TA=TL(if any leverage)+TE
2. ROA=R/TA, R=ROA*TA
3. ROE=R/TE
4. ATE=TA/TE

Assumed: ROA = 0.3 (0.3 Return for each 1 Total Assets employed)

Case 1:
TE=1, TL=0, so TA=1 and ATE=1.
Since ROA=0.3, so R=0.3, then ROE=0.3.

Case 2:
TE=1, TL=9 (loan to buy assets), so TA=10
"Leverage provides the ability to control more assets(9) than an owner would otherwise have the right to control."

and ATE=10. (Case 1 of ATE=1 vs. case 2 of ATE=10)
"This ratio tells us precisely how many more assets(9) an owner can control relative to their own equity capital."

Since ROA=0.3, so R=3, then ROE=3.
(Case 1 of ROE=0.3 vs. case 2 of ROE=3)
"As a consequence, it also measures how returns are magnified through the use of leverage.”

Thank you for your reply ! 再次感谢