This old professor insisted that he _____energetic enough and that he _____.
As we grow older,we learn the of our abilities.
1. ! There is a train coming.
9.―Your job ____ open for your return. ―Thanks.
8.Customers are asked to make sure that they ____ the right change before leaving the shop.
7.Although the causes of cancer ____, we do not yet have any practical way to prevent it.