【单选题】If the production possibilities curve is a straight line:
A.
opportunity costs increase as output of either commodity is expanded.
B.
resources are not equally substitutable between the production of the goods.
C.
opportunity costs are negative.
D.
as an increasing quantity of resources are shifted from one manufacturing process (good Y) to another (good X), there is no increase in opportunity cost.
【简答题】Directions: 1.Read the conversation and fill in the blanks with the information below 2. Listen to the tape and check your answer. here’s your key is that correct enjoy your stay may I help you we hav...