原子核由帶正電的質子和不帶電的中子所構成。
The atomic nucleus is composed of positively charged protons and uncharged neutrons.
Sottaku
About Sottaku
Sottaku is an app for learning Chinese, Japanese, Korean, English, Spanish, French, German, and Italian with a strong focus on SRS. It includes automatic flashcard creation for hundreds of thousands of words, grammar breakdowns in example sentences, language-specific study packs where available, adaptive quizzes, mobile apps, a browser extension, and community features. Give it a try now! All learning content is free with no limits on flashcards or study time.
Sottaku is built to match the habits of successful learners. By using Sottaku, you will naturally learn in the most efficient way possible, as proven by countless success stories in the language learning community.
Free Forever
Access all grammar guides, quizzes, and flashcards without paying a cent. Quality education should be accessible to everyone.
Smart SRS System
Our flashcard system uses the FSRS algorithm (also used in Anki) to optimize your review schedule and maximize retention.
Comprehensive Content
From hanzi, kana, hangul, and European vocabulary basics to grammar and reading practice where available, we have lessons for every level. Practice with quizzes tailored to your skill.
Community Chat
Ask level-appropriate questions and get help from the community. Learn together with fellow learners across all 8 supported languages.