Which of the following is a safe work practice to protect you from electrocution hazards?

Three out of five seniors remain undecided about a college major at the end of their senior year.

Write an essay on online collaboration, how to do it, the challenges, resolving the challenges, and consider whether the risks are greater than rewards. ( need )

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)?