good可以形容某人或某種東西很好,請問best也可以單用嗎?若best不能單用,要哪個英文單字才能形容"最好"呢?

推敲一下你在問甚麼：

He is good. = 他是一個好人

假如把best單用一般要加the.

He is the best. = 他是一個極(大)好人

假如這種best便是單用，跟「最好」的含意相同。

另外還有一些含意未必是"最好"的"單用"
Best wishes. 祝福
Best bet. 最大機會的/最有可能的
Try your best. 盡力/努力

The word "good" should be used.
good---that which is good;what is morally right, beneficial, advantageous, profitable.
do good is help:-Social workers do a lot of good.
do something for the good of HK--eg:-He works for the good of HK.
---eg:-I'm giving you this advice for your good in HK
do somebody good is to benefit him.Eat more vegetables and fruit for it will do you good.
to the good seen as balance on the right side and seen as net profit.Government were surplus to the good.Good and bad alike respect him as he is a good and virtuous person HK.