A．We should do our best every day．

B．It's World Earth Day!

C．What's the date today?

D．That's a good idea．

Kitty：Hi，Peter．{#blank#}1{#/blank#}

Peter：Let me look at the calendar．Oh，it's 22^nd April．

Kitty：Wow!{#blank#}2{#/blank#}

Peter：World Earth Day? I don't know before．What's that?

Kitty：It is to encourage people to save the Earth．

Peter：Oh! You mean we should do something to keep the Earth clean and healthy on this day．

Kitty：Yes，but not only one day．{#blank#}3{#/blank#}

Peter：I think so．Let's do something after school today．

Kitty：Yes．{#blank#}4{#/blank#}

Peter：See you then．

Kitty：See you!