Please help.

[WZ]

Do we use "1 years old" or "1 year old"?
Is "1/2" plural ?( 1/2 "meters" or "meter"?)
And what's the difference between:
(Over/during) the last two weeks...

Thank you.

[sc231426]

She is one year old.
She is the cutest one-year-old baby I've ever seen.

It's one half meters tall.
It's half a meter tall. (half of a meter tall)
It's one and a half meters tall.
It's two and a half meters tall.

"Over the past two weeks" and "during the past two weeks" mean exactly the same thing. I find that "over" is used more to describe overall trends from a broad vantage point, whereas "during" is used more to point out specific incidents. "During" states what happened; "over" is often used to emphasize the conclusion or application to the present.

Much criminal activity was reported during the past two weeks.
Much criminal activity has been reported over the past two weeks.
Crime has increased dramatically over the past two weeks.

[Pete]

It's one half meters tall.
When a positive number (like one half) is not greater than one, I'd probably be more likely to say,
- It's one half meter tall. It's one quarter inch long.

Of course when the number is greater than one, even if it has a fractional part, that number used with a noun to make a noun phrase is plural (as long as the noun phrase is not used as an attributive modifier).
- He's 1.8 meters tall.

[sc231426]

Thanks, Pete. I was debating with myself over "one half meter tall" and "one half meters tall." I think I've heard it both ways --thanks for the clarification.