How can I say, for example, "all that time I had been thinking that apple is a vegetable", but now I know that apple is a fruit, should I say "all that time I thought that apple is a vegetable" ? If both are correct what is the difference?
First, note that you need to talk about an apple or apples. If you just say 'apple', it means 'the substance called apple', eg There is not enough apple in this pie. Say eg All that time I had been thinking that an apple is a vegetable, but now I know that an apple is a fruit.
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First, note that you need to talk about an apple or apples.
If you just say 'apple', it means 'the substance called apple', eg There is not enough apple in this pie.
Say
eg All that time I had been thinking that an apple is a vegetable, but now I know that an apple is a fruit.
or
eg All that time I had been thinking that apples are