题目选项分析

Air traffic routes over the North Pole are currently used by only two or three planes a day, but it was found by a joint Canadian-Russian study to be both feasible as well as desirable if those routes are opened to thousands more commercial planes a year.

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.