此句取自p. 41 of 04.2022 National Geographic
A flat-topped peak high above the Amazon rainforest gives researchers a chance to identify new species and 【□】secrets of evolution. The biggest challenge: Getting there.請問空格內填入下列何者為最佳？
(1)unlocking
(2)being unlocking
(3)is unlocking
(4)unlock
譯：亞馬遜雨林內高聳的平頂峰提供了機會，讓研究人員能發現新物種與破解演化的秘密，但最大的挑戰在於：到達那裡。(這篇相當精采，與我們習慣的環境大不相同。透過閱讀多開視野是好的，不妨進入悠遊：https://www.nationalgeographic.com/magazine/article/untouched-by-time-this-pristine-world-soars-high-above-the-amazon-feature)
