题目

The Chinese manned submersible(潜水器) Fendouzhe, over 96.5 percent of whose core components have been independently developed by China, reached one of the deepest spots on the planet, a dizzying and dark depth of 10,909 meters.Extreme water pressure is the first challenge that requires dealing with during the exploration. At 10,000 meters down in the ocean, the submersible has to stand about 1,100 atmospheres of pressure, equal to 2,000 elephants stepping on a person’s back. As the solid “armour (盔甲)”，the manned cabin is a safety guarantee for humans to reach down to 10,000 met11．5名志愿者中安排4人在周六、周日两天参加社区公益活动．若每天安排2人，则不同的安排方案共有30种（用数字作答）．