What is the basic purpose of the international space station that will be completed in 2010?
a. it will be the largest artificial satellite.
b. it will direct all global communications.
c. it will be a space laboratory for scientists.
d. it will launch rocket-propelled weapons.

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Suppose there is a relation r(a, b, c) with a b+-tree index with search keys (a, b).1. what is the worst-case cost of finding records satisfying 10 < a < 50 using this index, in terms of the number of records n1, retrieved and the height h of the tree? 2. what is the worst-case cost of finding records satisfying 10 < a < 50 and 5 < b < 10 using this index, in terms of the number of records n2 that satisfy this selection, as well as n1 and h defined above? 3. under what conditions on n1 and n2, would the index be an efficient way of finding records satisfying the condition from part (2)?

Which feature is selected to practice and save the timing of a presentation