If you do not understand, you will not improve.

如果不理解，就无法提高。

youdao

The whole world can not understand, if you do not understand, I have something to say.

全世界都可以不懂，如果你也不懂，我还有什么话可说。

youdao

If you do not understand your friend under all conditions you will never understand him.

如果你不在所有的情况下了解你的朋友，你就永远不会了解他。

youdao

If you do not understand the difference between the different indexes each fund tracks, you run the risk of either doubling up on South Korea or excluding it altogether.

FORBES: Emerging Market Flavors Taste Differently At Schwab, Vanguard, iShares

If you do not understand the basis on which a firm is offering you redress, or have questions about the actual figures involved, you should first ask the firm to clarify how they have arrived at their calculations.

BBC: NEWS | Business | Ask the expert special: Endowments

D. level climate scientists that work at Columbia University's Earth Institute and even if you do not understand the physics of climate change or the computer models predicting global warming, common sense alone might lead you to think that human beings and their machines are making the planet warmer.

CNN: Why we should expect more weather disasters