Come usare i verbi SPEAK E TALK:che differenza c’è?

In generale c’è poca differenza fra speak e talk.
La maggior parte delle volte sono intercambiabili.

Vediamo alcuni esempi
When the  teacher of English  walked into the classroom, the students stopped talking.
Can I talk to the person in charge,please?

They stopped speaking to each another            + formale
'They have stopped talking to each another      + informale

Tenere una lecture (lezione,conferenza) informale
talk
Mister Rossi is going to talk about natural remedies for pets

Tenere una lecture (lezione,conferenza) su argomenti  più impegnativi
speak
Doctor  John Casey is going to speak on recent developments in genome biology
 

TALK
You're talking  rubbish!                     Stai dicendo stupidaggini
Don't talk nonsense                          non dire assurdità
Let's go for a coffee and talk it over    parliamone
Paul always talks about himself          parla sempre di sé
What are you talking about?
Babies walk at one and talk  at two
Roger, you talk in your sleep
Don't say anything about this to Peter. He talks  behind people's backs (= dietro le spalle)
George .We need to talk
She talks so much it gives me a headache.
That boy can never be quiet.He talks all the time

SPEAK
Everyone speaks well of Sara.She’s kind and sympathetic (comprensiva)I haven't spoken to Maria since last month
Luisa speaks  French and German
Can you speak up?I can’t hear you  ( alzare la voce)
The facts speak for themselves  ( parlano da soli)
He  always speaks his  mind ( dice quello che pensa)