Some blood types are quite common，others are regionally______，and still others are rare everywhere.

A．distributedB．contributedC．obtainedD．convinced

Some blood types are quite common，others are regionally______，and still others are rare everywhere.

1. A.
   distributed
2. B.
   contributed
3. C.
   obtained
4. D.
   convinced

Some blood types are quite common，others are regionally ________，and still others are rare everywhere．

A．distributed            B．contributed           C．obtained            D．contradicted