Electroconvulsive therapy (ECT) is usually reserved for difficult-to-treat depression patients who are not suitable for or have failed to respond to antidepressant medications.

电休克治疗（ECT）通常是不适合或对抗抑郁药物治疗无效的难治性抑郁患者的保留治疗方法。

youdao

This should only be your last resort, reserved only for those instances where tips one through four have failed.

这只能是你最后的方法，在之前四个方法都失败的情况下才能使用。

youdao

But the council reserved its harshest criticism for Israeli actions, saying Israel used disproportionate force and failed to take adequate measures to protect civilians during its campaign to silence Hamas rocket attacks.

VOA: standard.2009.11.04

Whereas Daley's approach to the competition saw him execute his trickiest dives first, Mitcham, 22, reserved a difficult routine for his sixth and final dive but failed to hold his nerve.

BBC: Commonwealth Games 2010: Tom Daley wins second gold