the usage of since

[chinalies]

Dear all,

This word really bugs me a lot in terms of its usage.

Please look at the following quotes from other websites, particularly the news websites.

Dow finishes below 12000, longest losing streak since 2002
Dow sinks below 12000 for the first time since March; stocks head
U.S. Stocks Fall as Dow Has Longest Slump Since 2002 on Economy
The Stock Market has Dropped 2500 pts Since Obama Took Over

I am just wondering how I am supposed to write the sentences. Since junior high school, I was taught rules about the tenses.

When the word 'since', as far as i can remember, refers to the meaning ' from a certain point of time until today/now/the present moment', the sentence structure shall be in the present/past perfect tense. Examples are listed as below,

1. I have been wearing glasses since I was 12.
2. I have only been hospitalized once since i was born.
3. It has been/ is years since i saw you last time.(this is an exception).
4. I havent slept since last night.
5. She has been upset since she broke upwith her boyfriend.
6. She said that it had been years since her last visit to that city.

so I am wondering why news today opt for the simple tense like those quoted here.

Please enlighten me a little bit.
P.S. I am a financial translator, usually from English to Chinese, but sometimes from Chinese to English (which usually will give me a head when the topic talks of stuff associated with since or from ... until ... or from... onwards).

[Barb_D]

The first three are all in headline style. Headlines don't follow the same grammatical rules as normal prose. The tenses are different, articles are omitted, etc.

The fourth one uses the present perfect.

[5jj]

2. I have only been hospitalized only once since i I was born. You will see and hear your version, but purists prefer this order.
3. It has been/ is years since i I saw you last time.(this is an exception).

[emsr2d2]

"It has been/ is years since i I saw you last time"

It has been years since I last saw you.
It is years since I last saw you.
It's years since I last saw you.

[I haven't seen you for years.]