Not until all the fish died in the lake __________ how serious the pollution was.
As we grow older,we learn theof 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.