... 第四级 Fourth scale-step 第四类（对位） Fourth species 四五挂留音 Fourth to five suspension ...
双语例句
1
They also found a fourth possible new species and other corals that were thought not to inhabit the waters around the Galapagos.
他们还发现了第四个可能的新物种，以及其他一些被认为不在加拉帕戈斯群岛附近海域生长的珊瑚。
2
Three of the four gorilla subspecies are already considered critically endangered, and the fourth is listed as endangered on the IUCN Red List of Threatened Species.
Madagascar, which has been isolated from landmasses for more than 160m years, is the world's fourth largest island and a "conservation hotspot" with thousands of exotic species found only here.