Tense switching

Hi,

I have seen tense switching occurring many times when I don't see a good reason. I posted some of these sentences before and was told not to change tenses. Here's another sentence and it's from CNN. If you think the writer used it wrongly, could you please tell me what was in his head when he wrote that so I can at least understand what he/she was thinking.

South African police and military units raided three hostels Thursday in a clampdown on xenophobic attacks that have left more than 40 dead, authorities said.

The raid was last Thursday. The deaths may or may not have occured before the raid. .

The reporter is considering the time that the authorities 'said ' this to be 'present time', because they probably said it very recently.

Here's another.startclickprintexclude>

Police said 42 people have been killed in the violence, which began last week in Johannesburg's Alexandra Township and has been concentrated in the city's poorest areas.It's the same general idea here. The violence began last week. The killing and 'concentrating' have occured in the period from then up to the present time.

Let me know if you need more explanation.

best wishes, Clive

New2grammar

I need a third opinion.

I met an old high school friend ... yesterday. It had been three years since we'd talked.  << This is technically correct.

I met an old high school friend ... yesterday. It has been three years since we've talked.  <<  Acceptable to my ear, probably because yesterday is so recent that we can include it psychologically in the same broad present in which this conversation is occurring.  This is nevertheless technically 'wrong'.  But note that sometimes what is 'wrong' from a strict mathematical view of time relationships is quite idiomatic linguistically and psychologically.

However, my ear would not like this:

That was the year I ran into an old high school friend -- 1995 I think it was.  Anyway, it has been three years since we've talked.  (NO!  Here my ear would want had been and we'd.) 

CJ 

Actually, the message was meant for Optilang in case s/he asked why I reposted the same question. Apparently, it was a bad joke.

Thanks, CJ for the Third opinion :)

New2grammar

Can I say the following, I met an old high school friend at the grocery store yesterday. It has been 3 years since we'd talked.

New2grammar

It should be "It had been 3 years since we'd talked". Could it be correct, loosely speeking?