题目选项分析

A newly released study on the tectonic plates forming the Pacific basin indicates that by the time they have shifted even a few miles, a vast percentage of the coastline currently home to major world cities already will have become entirely submerged because of global warming

A newly released study on the tectonic plates forming the Pacific basin indicates that by the time they had shifted even a few miles, a vast percentage of the coastline which is currently home to major world cities, because of global warming, will have already become entirely submerged