8. He was so deep in thought, thinking of the problem ______ he knocked into the tree without noticing it.
. Water can absorb and _______ a lot of heat without big changes in temperature.
. Han Han, a young writer, is famous _______ his novels.
. Of all the works Stevenson has written, Treasure Island is probably his _______ work.
. The reason for their failure, you know, was _______ they didn’t get fully prepared for it.
. . John promised his parents he _______ not smoke again, and he has not smoked ever since.