题目内容：

Earth Day is a reminder__we need to care about the world we live in
and__we should learn to respect life and nature.
A.that；that B which；which C that；what D which；what
为什么选A

优质解答

同位语从句必须用that
reminder以后的内容,都是reminder的解释,是reminder的同位语,所以用that引导