3. Judging from the document, what was an important purpose of Zheng He's voyages?

offline recommendation systems option b

because recommendation systems produce a list of two ways

1. through collaborative filtering

or

2. through content-based filtering

ba geologist finds four sedimentary rock she determines that no geologic events have shifted the layers she labeles them a,b,c,dbfrom top to bottom

the answer is actually b.   as habitats are destroyed, animals and plants may become extinct.   , according to edge nuity