11.   The researchers also have collected a separate database with American Indian, Asian and European DNA to cross-reference genes that cannot be traced to Africa.

a. + database >>共 315
relational 6.58%
national 6.08%
online 3.50%
electronic 3.42%
new 3.25%
central 2.83%
large 2.67%
computerized 2.58%
huge 2.42%
searchable 2.33%
separate 0.92%
separate + n. >>共 1252
incident 4.65%
meeting 2.72%
state 1.93%
company 1.87%
report 1.81%
attack 1.55%
case 1.51%
talk 1.46%
way 1.32%
entity 1.20%
database 0.06%
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