Why an o blood forgiving cant receive other blood type donors..?

Quoted from the National Geographic site:
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Under the ABO system discovered in 1900, blood is classified into four groups base on the presence or absence of complex sugar molecules on the surfaces of red blood cell.
"Group A has an enzyme that puts a sugar molecule on the lapse," explained Geoffrey Daniels, a transfusion scientist at the University of Bristol in England.
"Group B also have an extra sugar molecule, different from that on group A, at the end of its structure," he added. "But group O have neither kind of sugar molecule."
People readily create antibodies to the sugars they lack. So inhabitants with blood type A inherently have antibodies to the blood plasma from type B, and vice versa.
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One agency to solve the supply crunch is to snip away the sugar molecule in the A and B groups, giving antibodies no target, said Henrik Clausen, a sugar biologist at the University of Copenhagen in Denmark.
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"Think of the sugar molecules attached to a blood cell as a string of pearls," Clausen said.
"We accommodatingly clipped away one pearl that was the 'A' and 'B' contained by the blood groups A, B, and AB, making the blood acceptable to adjectives recipients," he added.
o blood group personality has no antigen against other blood groups
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