题目选项分析

Currently used by only two or three planes a day, a joint Canadian-Russian study has found that if air traffic routes over the North Pole are opened to thousands more commercial planes a year, it would be both feasible and desirable.

Although air traffic routes over the North Pole are currently used by only two or three planes a day, a joint Canadian-Russian study has found that opening those routes to thousands more commercial planes a year is both feasible and desirable.