1 . Now, we scientists ________ _________ ______ ______ _______ it is perfectly possible to live and not know.
如今，我们科学家理所当然地认为，生而有所不知是完全有可能的。

2 . When they failed to produce any promising results, Tu _________ _________ the ancient books of traditional Chinese medicine again.
当这些未能取得任何有希望的效果时，屠呦呦就再次查阅中医典籍。

3 . Over the past 50 years, about 17 per cent of the rainforest ________ ________ ________ _______ human activities such as agriculture and cattle farming.
在过去的50年里，由于农耕和养牛等人类活动，大约17%的雨林已经消失。

4 . The Amazon River, ________ _________ the rainforest gets ________ name, is close to 6,400 kilometres _________ _______—roughly 100 kilometres longer than the Yangtze River.
亚马孙雨林得名于亚马孙河，亚马孙河长约6,400千米， 比长江还长大约100千米。