First, read the English article below.

Unless you're falling from an airplane, you won't have enough time to try this step. Maximize your surface area by spreading yourself out using this skydiving technique.  Position yourself so that the front of your body faces the ground. Arch your back and pelvis and tilt your head back like you're trying to touch the back of your head to the back of your legs Extend your arms and bend your elbows at a 90 degree angle so that your lower arms and hands point forward (parallel to, and on the sides of, your head) with your palms facing down; spread your legs to shoulder width. Bend your knees slightly.  Do not lock your legs and keep your leg muscles relaxed and fall into the motion to absorb most impact. For very high falls, the surface on which you land is the greatest influence on your chance of survival.  Search for steep slopes that gradually grow gentler, since you will not lose all of your momentum at once when you hit the ground. Observe the terrain below you as you fall.  Hard, inflexible surfaces such as concrete are the worst on which to fall.  Very uneven or jagged surfaces, which present less surface area to distribute the force of impact, are also undesirable. The best possible surfaces on which to fall are those that will compress or give way when you fall on them, snow, soft ground (such as a newly tilled field or in a marsh), and trees or thick vegetation (although these present a high risk of impalement). Water is only safe to fall into up to around 150 feet (45.7 m); past this height it will be little better than falling on cement as it cannot be compressed. Falling in water also presents the high risk of drowning (since you will most likely be knocked unconscious). Water is much safer to fall into if it is frothy and bubbly. If you're falling from an airplane, you will usually have about 1-3 minutes before impact. You will also have the ability to travel horizontally a good distance (up to a couple of miles or three kilometers).  From the arch position described above, you can direct your... 

Now, please write a short abstract for it in Vietnamese. Abstract:
Giảm tốc độ rơi bằng tư thế ưỡn người ra. Tìm vị trí tiếp đất tốt nhất. Hướng cơ thể về vị trí tiếp đất. Sử dụng đúng kỹ thuật tiếp đất.