They talk______a long time. What are they talking______?

for
about

They talk for a long time. What are they talking about?
他们聊了好久。 他们都说了些什么？

for ,about
第一句,怎么觉得应该是:They have talked for a long time更对呢

They talk for a long time. What are they talking abuot?

over
about

for about