Part of the reason Charles Dickens loved his own novel, David Copperfield, was ________ it was rather closely modeled on his own life.(2010·北京)

The reason for her failure is_____she was too proud.

_______ is even important is ______ as the earth cooled down, water began to appear on its surface.

What we really concern is _____ those orphans can recover from the earthquake psychologically.

---I’ll ask the teacher about past tense. I’m very puzzled about it. --- That is just _____ most of our classmates have doubt.