选择方框内的单词完成下列句子， 使句子通顺、正确。
A. knowledge  B. twentieth  C. largest  D.  written  E.  hungry  F uncomfortable.
Bruce is _______ , so he can’t go to school today .
He lives on the _______ floor . He uses a lift to go up and down.
China has the _______  population in the world .
The books _______ by Mr White are very interesting .
I’m not _______  , but I’m a little thirsty .
Our _______ of the universe is growing all the time .