If you like to sing... Singing can help you focus on pronunciation in a different way - it makes imitation easier and lets you forget about grammar while you focus on your sounds.
Common American Phrases -- This can be useful for conversational English and for cultural understanding.
Basic American Grammar and Usage -- Here is a good general purpose grammar book.
Phrasal Verb books
Phrasal verbs are used VERY frequently in spoken English, but are found MUCH LESS frequently in written English. If you want to speak English with more natural vocabulary, you should study phrasal verbs.
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