Grammar Tip 2: Double Subjects

Look out for cleft sentences in English that have effectively two subjects. Often the two subjects are separated by a word like 'what', 'how' or 'when' and the verb comes at the end:

I don't know what she said.
I can't say how we did it.
I can tell you when she is coming.

Sounds easy. But note that if you specify the second subject (Ie not just using words like 'she' or 'it'), the verb still comes at the end of the sentence:

I don't know what the argument was about. (NOT: I don't know what was about the argument.)
I don't know how the weather will turn out.
I can tell you when the train to London that you have a reservation for is supposed to leave.

You can also use 'what' before both subjects:

What I don't know is what she said.

And also 'it' can be used with 'that' for emphasis:

It is what she said that I don't know.