1．It is worthwhile to_have/having (have) spent so much time on it，for the result is satisfactory.
2．(2019·山西沂州一中期中)What he has done is in disagreement(disagree) with what he has said.
3．I am too nervous to_answer (answer) such an easy question correctly.
4．My advisor encouraged me to_take(take) a summer course to improve my writing skills.
5．(江西卷)It is unbelievable that Mr. Lucas leads a simple life despite his great wealth.
6．I wish I could do something in return for_the kindness I have received from him.
7．The United States is_viewed(view) as a melting pot of different nationalities.
8．(2017·江苏卷)Human beings will continue to adapt to the changing climate in both ordinary and astonishing(astonish) ways.
