It's hard to understand

理解───understand;难以───difficult to

Do you understand the working of this machine?───你懂这部机器是怎样工作的 吗 ?

I can never understand why Mary said nothing about her wrongs.───我毫不理解玛丽说她什么也没有做错.

I quite understand," he replied.───我很理解”，他回答道。

Not all doctors truly understand the reproductive cycle.───并非所有的医生都真正了解生殖周期。

He doesn't understand me, or at any rate not fully.───他並不了解我, 至少是了解得不全面.

He gesticulated wildly as he tried to make her understand.───他使劲向她做着手势,试图让她明白.

You have to explain it in terms that the man on the Clapham omnibus would understand.───你必须用老百姓能理解的语言来解释这事.

With his owlish face, it is easy to understand why he was called "The Professor".───看看那张严肃而又睿智的猫头鹰脸，就不难理解他为什么被称为“教授”了。

There needs a long apprenticeship to understand the mystery of the world’s trade.

understand yourself in order to better understanding others.

All right, all right. I understand.

Not all doctors truly understand the reproductive cycle.

I don't understand what he's saying.