另外，经典力学并不是一门简单的学科，对于许多人来说，他可能是他们将要面对的最困难的一门。
On the other hand, it is not an easy subject. For many people, it is the most difficult subject they will ever encounter.
另外，经典力学并不是一门简单的学科，对于许多人来说，他可能是他们将要面对的最困难的一门。
On the other hand, it is not an easy subject. For many people, it is the most difficult subject they will ever encounter.
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