下列各句表现不同的交际情境，其中表达得体的一句是

I turn on the TV for you，Grandpa?一Yes，thanks a lot，my dear. You’re so considerate.

The headmaster was dismissed three months ago.The post is too important to leave　　any longer,especially before the college entrance examination.

It’s the protection for the trees ______ really matters, ______ how many trees are planted each year.[ ]

24．One recent prediction is that within the next 50 years, it ______ possible to link the human brain directly with a computer