The following grammar sentences need to follow the rule of "Dangling Modifiers",if they need no change write no change.

1.Flying over the oak tree, the farmer saw the flock of birds that had damaged his crops.
My answer:The farmer saw the flock of birds that had been flying over the oak tree and damaging his crops.

Ms.Sue,
You had said that my answer was correct
but after i kept rereading it i feel that theres something wrong. So i came up with a different answer please let me know what you think.

Flying over the aok tree, a flock of birds the farmers crops.

You need to to proofread and watch out for your typos in these posts...especially your latest sentence revision.

I woud suggest the following:

The farmer saw the flock of birds that had damaged his crops flying over the oak tree.

The birds are doing the flying rather than the farmer.

I hope this helps. Thanks for asking.

1.Flying over the oak tree, the farmer saw the flock of birds that had damaged his crops.
My answer:The farmer saw the flock of birds that had been flying over the oak tree and damaging his crops.

Ms.Sue,
You had said that my answer was correct
but after i kept rereading it i feel that theres something wrong. So i came up with a different answer please let me know what you think.

Flying over the aok tree, a flock of birds the farmers crops.

Did you mean to say, "Flying over the oak tree, a flock of birds DAMAGED the farmer's crops"? Your first answer is better because the birds didn't eat the crops while they were flying over the oak tree. Frankly, I don't there is a good way to fix this in one sentence. But -- how about? --
The farmer saw the same flock of birds flying over the oak tree that had damaged his crops.

Ironing out all wrinkles, the pants looked much more presentable.

To fix the sentence with a dangling modifier, you need to ensure that the subject of the modifier is the doer of the main action. In this case,

"Ironing out all wrinkles, the pants looked much more presentable."

The modifier "Ironing out all wrinkles" is describing the action, but it is unclear who or what is doing the action. To fix this, you can rephrase the sentence to make it clear who is doing the ironing:

"The pants looked much more presentable after all wrinkles were ironed out."

In this revised sentence, it is clear that someone is ironing out the wrinkles in the pants.