警报器鸣响，预示着一辆救护车正在靠近。

The siren signaled the ___approach of an ambulance.

请系好安全带，飞机现在正开始降落在希思罗机场的最后进近。

Please fasten your seat belts, the plane is now making its final ___approach into Heathrow Airport.

随着最终期限的临近，团队夜以继日地工作。

With the ___approach of the final deadline, the team worked around the clock.