标题: 请教版主 GWD17-Q32 [打印本页] 作者: larryywddd 时间: 2011-1-13 22:09 标题: 请教版主 GWD17-Q32 Navigators have known for thousands of years that the ocean has variable currents, but it is only in the last half century that a reasonably clear picture has emerged of the patterns and causes of ocean currents.
1 a reasonably clear picture has emerged of the patterns and causes of ocean currents
2 a reasonably clear picture of the patterns of ocean currents and their causes have emerged
3 a reasonably clear picture emerged of ocean currents, their patterns and the causes of them
4 there have emerged a reasonably clear picture of the patterns of ocean currents and what caused them
5 there had emerged a reasonably clear picture of the patterns of ocean currents and their causes
B D 选项中的 为什么要改成has 呢？ 谢谢 作者: larryywddd 时间: 2011-1-13 22:10
UP~