1. 请先从表格中选用本单元所学单词完成下列短文，然后核对答案并背诵该短文。(文中加波浪线的句子为本单元的语法项目：复习名词性从句)

expansion, bury, think twice, fall into ruin, throw oneself into

While diving in the deep waters of a trench, some divers happened to find a whole city beneath the waves as well as a wreck of a ship, which was full of corals. This discovery intrigued some archaeologists. They immediately studying the history of the city and how it . In the middle of the investigation, they suddenly found some mysterious creatures swimming around them. They subdued their fear and continued their study. But with the of the number of these strange creatures, they found it not safe to continue staying in the water. After , they decided to abandon the city as well as the ship and retreat. After all, life is the most important.