This year marks Earth Day's 50th birthday. It was created to remind people to ________ the earth﹣the home to all the living things.( )
talk about
care about
hear about
The water dark and dirty.It's no longer safe to drink.( )
became
has become
will become
was becoming
Last night,the shop was closed she didn't buy any chocolate.( )
so
if
or
when
Some old people need a _______ because they feel lonely.( )
gift
stick
pet
watch
By the time the teacher came, we ______ cleaning the classroom.( )
finished
have finished
had finished
_____ walk on the grass.( )
Doesn't
Don't
Not