salad是可數名詞嗎為什么有時候+s

　　例句：

　　The salad had lost its crispness.

　　這色拉已經不脆了。

　　Can I help you to some more salad?

　　再給你來點色拉好嗎？

　　I think I'll go for the fruit salad.

　　我想要水果色拉。