Can you work out the maths problem?— Sorry, I can ______ understand its meaning.

I have a dog. _____ name is Wangwang.

I have been living in London for more than ten years, so I have ________ good knowledge of this city.

Does anyone know _______ girl with a book in her hand over there?—I’m afraid no one knows.

As we all know, it’s not polite to keep others _____ for a long time.