Question 13 is based on the passage you have just heard.

Passage Two 

听力原文

        At the beginning of the twentieth century, on the Gulf Coast in the US state of Texas, there was a hill where gas leakage was so noticeable that schoolboys would sometimes set the hill on fire.

        (12) [Pattillo Higgins, a disreputable local businessman, became convinced that there was oil below the gassy hill.] Oil wells weren’t drilled back then. They were essentially dug. (13) [The sand under the hill defeated several attempts by Higgins’s workers to make a proper hole.] Higgins had forecast oil at 1,000 feet, a totally made-up figure. Higgins subsequently hired a mining engineer, Captain Anthony Lucas. (14) [After encountering several setbacks, Captain Lucas decided to use a drill, and his innovations created the modern oil drilling industry.] In January 1901, at 1,020 feet, almost precisely the depth predicted by Higgins’s wild guess, the well-roared and suddenly ejected mud and six tons of drilling pipe out of the ground, terrifying those present. For the next nine days until the well was capped, the well poured out more oil than all the wells in America combined.

        (15) [In those days, Texas was almost entirely rural, with no large cities and practically no industry. Cotton and beef were the foundation of the economy. Higgins’s well changed that.] The boom made some prospectors millionaires, but the sudden surplus of petroleum was not entirely a blessing for Texas. In the 1930s, prices crashed, to the point that, in some parts of the country, oil was cheaper than water. That would become a familiar pattern of the boom-or-bust Texas economy.

13. What prevented Higgins’s workers from digging a proper hole to get the oil?（是什么妨碍了希金斯的工人挖一个合适的洞来获取石油？）

解析：C。录音中提到，希金斯的工人们几次都想尝试挖个合适的洞，但都被山脚下的沙子给难住了。C项The sand under the hill为原词复现，因此选C。

错项排除：A、B、D项的gas underground、needed skill和suitable tools在录音中均无依据，故可排除。