___ pen is red and ___ is red, too.

Copernicus’s theory is now the basis ______ all our ideas of the universe are built.

I have you asked John to come to the party thisevening–Yes，I have，but he＿＿＿＿

he sick mother got up, she was surprised to findthat her six-year-old daughter _______ in the kitchen

1I think _______ our duty to keep our environment clean andtidy.