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

在这种情况下, 提高你习效率至关重要。

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”，替代这个词，你可以说：“一个人”，“己”，“他们己”。

One doesn't do it by oneself.

一个人不能独做这件事。

One could carry this television by oneself.

这台电视可以己搬。

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.

抛弃祖先积累关如何来之不易知识，或者期望独发现一套可行目标，是错误傲慢。

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，在一个嘈杂拥挤世界里，人们应该抽出时间独处，远离吸引注意力刺激。