Read the text and choose the correct answer. Precious metals What is known as the 'California Gold Rush' took place in the US in the middle of the 19th century. Miners searched for gold, silver and copper in the (1) ............. of becoming rich. As they dug, they (2) ............. piles of unwanted dirt and rocks. The miners who worked there so long ago would have been amazed to know that over 150 years later, these waste products are in (3) demand. Geologists have analysed samples and discovered that some of them contain valuable minerals, called rare earth elements, which are used in the production of (4) .............. electronic devices. Rare earth elements are not actually very rare, but they are (5) to mine. This is mainly because they (6) .............. naturally in very small quantities and are difficult to (7) from other elements surrounding them. In (8) ............., the precious minerals are relatively easy to extract from the 19th century mines' unwanted waste products. 1. A. luck B. hope C. chance D. wish 2. A. raised B. built C. created D. developed 3. A. great B. large C. grand D. big 4. A. frequent B. wanted C. popular D. daily 5. A. uneasy B. stubborn C. clumsy D. awkward 6. A. occur B. happen C. arise D. reveal 7. A. divide B. separate C. undo D. disconnect 8. A. conflict B. difference C. opposition D. contrast​
