12. Most nations regard their airspace as extending upward as high as an aircraft can fly; no specific altitude, however, has been officially recognized as a boundary. (A) as extending (B) as the extent (C) to be an extent (D) to be an extension (E) to extend 这题划线的UPWARD不在A里, 我想问,B选项为什么不对? 原文划线部分怎么理解才好呢?
23. A huge flying reptile that died out with the dinosaurs some 65 million years ago, the Quetzalcoatlus had a wingspan of 36 feet, believed to be the largest flying creature the world has ever seen. (A) believed to be (B) and that is believed to be (C) and it is believed to have been (D) which was, it is believed, (E) which is believed to be 我想知道大家对B和C选项是怎么选择的? 谢谢!
23. A huge flying reptile that died out with the dinosaurs some 65 million years ago, the Quetzalcoatlus had a wingspan of 36 feet, believed to be the largest flying creature the world has ever seen. (A) believed to be (B) and that is believed to be (C) and it is believed to have been (D) which was, it is believed, (E) which is believed to be 根据句意应该用完成时态。has ever seen是关键的决定。and that在这里指带不清。因为是说Quetzalcoatlus is believed to have beenthe largest flying crea,而不是她的翅膀
an extended discussion: 长时间的讨论; an extended meaning : 引伸的含义
3.extent(N.):
1).to a certain extent/to some extent/to an extent (=partly) 2).They examined the extent to which (=how much) age affected language-learning ability. 3).To what extent (=how much) did she influence his decision? 4). to such an extent that/to the extent that (=so much that) Violence increased to the extent that residents were afraid to leave their homes. The shelf extends 20 cms from the bookcase. 5)extent of Considering the extent of his injuries he's lucky to be alive. It's too early to assess the full extent of the damage.