In such a case, studying by oneself is crucial to improve your learning efficiency.

在种情况下, 学对于提高你的学习效率至关重要。

And now for " by oneself." " By" is a preposition.

现在讲by oneself。by是介词。

" Alone" , instead of saying " alone" , you could say: " by oneself" , " on one's own" , " by themselves" .

“独”，个词，你可以说：“个人”，“己”，“他们己”。

One doesn't do it by oneself.

个人不能独做件事。

One could carry this television by oneself.

台电视可以己搬。

To discard the hard-won information on how to live accumulated by our ancestors, or to expect to discover a viable set of goals all by oneself, is misguided hubris.

抛弃祖先积累的关于如何生活的来之不易的知识，或者期望独发现套可行的目标，是错误的傲慢。

In a noisy and crowded world, they argue, people should make time to be by oneself, away from attention-grabbing stimuli.

他们认为，在个嘈杂拥挤的世界里，人们应该抽出时间独处，远离吸引注意力的刺激。