Conditionals are used to express both real, likely and unreal situations. As a result, tenses used with them are not flat; they change. That is why the difference between ‘If I arrive’ and ‘If I had ...

'Can', 'could', 'be able to', 'manage to' Present tenses Present perfect continuous Quantifiers Phrasals First and zero conditional We talk about unreal or imaginary situations using the second ...