Question

I t is___to say "Thank you. " when you get something from others.

A a bad manner B bad maners C a good matter D good matters 选什么呢？
请解释下为什么谢谢各位高手！！
答案是D，，，。。我也选c，不对啊

Answer 1

It is a good manner to say "Thank you." when you get something from others.
'It' 形式主语，真正的主语是 to say " Thank you." 系动词是 is, 单数形式，所以用 a good manner.
还原：To say " Thank you." is a good manner when you get something from others.

Answer 2

a good manner

Answer 3

C a good matter 完全赞同二楼的说法！