difficult sentence

[adel87]

dear
in theses sentences

Colonel O'Neill ordered us to lay down|cover fire while Daniel Jackson dialled home.
what is the meaning of lay down
Now, there is some light filtering through up there and there are ..
what is the meaning through up
You wouldn't think jagged bone digging|into raw nerves would hurt, but it does.
what is the meaning of raw nerves
over the borders of Iran and Iraq ..

what is the meaning of over the borders
thank you a lot

[SoothingDave]

dear
in theses sentences

Colonel O'Neill ordered us to lay down|cover fire while Daniel Jackson dialled home.
what is the meaning of lay down
Now, there is some light filtering through up there and there are ..
what is the meaning through up
You wouldn't think jagged bone digging|into raw nerves would hurt, but it does.
what is the meaning of raw nerves
over the borders of Iran and Iraq ..

what is the meaning of over the borders
thank you a lot

Not a teacher.

"To lay down cover fire" means to shoot at the enemy in order to keep him down. (This is presuming that both sides are within range and hiding behind something.) Jackson wants to use the phone, but if he gets preoccupied with using that equipment, he would be defenseless and may get shot.

So, you initiate firing on the enemy to keep him down. This prevents him from taking the offensive and firing on you. This is called "covering" as well, as in "cover me, I'm going to move over there."

"Through up" is not an expression. Light is filtering through. Where? Up there.

"Raw nerves" on a body are a place that is sure to cause discomfort when touched. By metaphor any subject or activity that causes irritation or agitation to another person or party can be described as "touching a raw nerve."

"Over the borders" seems to just mean that this is the subject that causes the raw nerves. Iran and Iraq fought a war in the 1980s. The subject of exactly where the border is is still a matter of dispute in both countries. It's a raw nerve.