Complete English Grammar is available in this app.
You can improve your grammatical skills from basic to advanced levels.
The interface of this app is very nice and completely suitable for reading.
Contents:
Word: The Definition & Criteria
Sentence: Definition & Types
Parts of Speech
Noun: Definition & types
Pronoun: Definition & Types
Adjective: Definition & Types
Verb: Definition & Types
Preposition: definition & Types
Use of Prepositions
Conjunction: Definition & Types
Interjection: Definition & Types
Article: Definition & Types
Rules of Using Articles with Examples
Tenses
Phrase: Definition, Types & Examples
Number: Types, Rules & Examples
Clauses: Definition, Types & Examples
Conditionals: Definition, Structure & Examples
Modal Auxiliaries
Mood: Definition, Types & Examples
Subject-Verb Agreement: Rules & Examples
Right Forms of Verbs: Rules with Examples
Case: Definition, Types & Examples
Transformation of sentences
Modifiers: Definition, Types & Examples
Narration: Reported to Reporting Speech
Determiners & Quantifiers
Prefixes: Definition with Examples
Suffixes: Definition with Examples
Types of Questions: Open-ended and Closed-ended
Punctuation: Definition, Types & Usage Rules
Do-insertion or Do-support
Negation: Definition, Rules & Examples
Inversion: Definition with Examples

More updates would also be published.