- 
					1 billion worldwide who live with unsafe drinking water. 2019年12月四级真题(第二套)阅读 Section A
- 
					About a million bottles are bought every minute, not only by thirsty tourists but also by many of the 2.1 billion worldwide who live with unsafe drinking water. 2019年12月四级真题(第二套)阅读 Section A
- 
					It turned out that, when the mice were hungry, they ventured into the unsafe areas for food. 2018年6月四级真题(第二套)听力 Section C
- 
					Twelve regions were listed as unsafe on Wednesday, on Thursday, eight remained. 2019年12月四级真题(第二套)阅读 Section B