speak、talk、say、tell 都有“說”的意思，但它們的意義和用法不同。

speak“講話、發言、演說”,后面跟人做賓語要加介詞 to, speak 作及物動詞時后面跟各種語言；

Can you speak French? 你會說法語嗎？

Who will speak at the meeting? 誰將在會上發言？

May I speak to John, please? 我能和約翰講話嗎？或 請找約翰接電話好嗎？

常用的短語：

speak out 暢所欲言，直言不諱的說

speak up 大聲說，毫不猶豫地說出

talk“談話、閑談”,是不及物動詞, 后面跟人的時候用介詞with、to 等, 后面跟“事情”要用到介詞about ；

Who is talking to your mom? 誰再和你媽媽聊天？

Mr. Chen wants to talk to you. 陳老師要和談談。

What are they talking about? 它們在聊啥？

talk 常見的短語還有：

talk down ：以高聲或連續的話說出

talk into 說服......做......

talk of 談到，表示要

talk over 討論（事情）

say 是及物動詞，表示說的內容，即說了什么話；

What did you say? 你剛才說啥來著？

He said he would come to join us. 他說他回來加入我們。

Say no to smoking. 拒絕吸煙。

What he said made me very sad. 他說的話叫我很傷心

tell 表示“講述、告訴”是及物動詞, 后面首先要跟人, 然后再跟從句或者介詞短語等。

Tell me if you need any help. 需要幫忙說一聲。

Have you ever told a story about ghosts？你講過鬼故事嗎？

To tell you the truth, I don't like ghost stories. 說實話，我們不喜歡鬼故事。

另外，tell the difference 意為區別，如：

I can't tell the difference between you two. 我分辨不出你們倆誰是誰。