11.   (A) How to care for precious metals. 
(B) A standard unit for measuring weight. 
(C) The value of precious metals. 
(D) Using the metric system.   

12.   (A) To check the accuracy of scales. 
(B) To calculate the density of other metals. 
(C) To observe changes in the atmosphere. 
(D) To measure amounts of rainfall.   

13.   (A) Someone spilled water on it. 
(B) Someone lost it. 
(C) It was made of low quality metal. 
(D) The standard for measuring had changed.   

14.   (A) It is a small amount to pay for so much precious metal. 
(B) It is difficult to judge the value of such an object. 
(C) It is reasonable for an object with such an important function. 
(D) It is too high for such a light weight.   

15.   (A) He is unable to attend her class. 
(B) He wants to deliver something to her office. 
(C) He wants to hand in a late assignment. 
(D) He wants to drop her course.