设向量函数A（t）=2cost，sint，t），则导数向量为（）。 A: -2sint，cost，1 B: 2sint，cost，1 C: -2sint，sint，1 D: -2cost，sint，1

Fixed Cost，Veriable Cost，Explicit Cost，Implicit Cost，Opportunity Cost，Sunk Cost，Economic Profit，Normal Profit，Average Cost，Margial Cost

Three cost drivers are used to estimate the cost of processing insurance claims. The cost drivers are: (1) claim amount, (2) age of vehicle in accident and (3) age of driver in accident. The percentages attributable to the cost drivers are 50% for claim amount, and 15% for each of the other two cost drivers. What is the cost to process Claim #101? The claim amount is $1,000. The age of the vehicle is 5 years. The age of the driver is 20 years.

This book______me twenty dollars. A: is cost B: was cost C: cost D: have been cost

Berhman saved Johnsy _____ his own life. A: at any cost B: at no cost C: at the cost of D: in the cost of

What type of cost is the supervisor salary cost, when one supervisor is needed for every ten employees added to the staff A: A fixed cost B: A variable cost C: A mixed cost D: A step cost

What type of cost is supervisor salary cost, where one supervisor is needed for every ten employees added to the staff? ( ) A: Variable cost B: Fixed cost C: Semi-variable cost D: Step cost

A cost accounting system typically includestwo processes: cost allocation and cost determination.

What is the base of selling price A: the cost of production B: a percentage of total cost C: the cost of transportation D: the cost of storage.

向量函数r(t)=(cost，sint,1)的导数的模等于