用所给单词的适当形式填空。
It’s never too old to learn. Karl Marx began to learn English in his _______(forty).
We should be brave when we meet illness and _____________(difficult).
Learning some knowledge of psychology is _____________(value)to all the teachers.
We__________(simple) can’t wait for the fashion show tomorrow.
Mr. Brown will give some________(speak)on how to improve English next week.