They will have gotten through the psychological adjustments necessary to make it practical and sustainable, should they wish to continue. =

They will have gotten through the psychological adjustments necessary to make it practical and sustainable, if they should wish to continue.

▲ 这里的 should 是情态动词，用在条件从句中，表示事件将来发生的可能性，意为“将要；假定要；可能要”。该结构的特点是：

（1）should 表示“将来的可能性推测”，不表示虚拟语气。

（2）主句也使用陈述语气。

（3）去到 if 后，should 提到句首，构成倒装语序。

▲《柯林斯词典》对此的解释是：You use should in conditional clauses when you are talking about things that might happen. 词典的例句是：

If you should be fired, your health and pension benefits will not be automatically cut off.

如果你被解雇，你的医疗和养老保险金不会自动中断。

Should you buy a home from Lovell, the company promises to buy it back at the same price after three years.

如果你从洛弗尔公司买房子，该公司承诺3年后以同样的价格再购回。

▲ 再举几个其他例句：

1. If you should feel worse, please call our nurses at the Triage immediately. 如果您觉得身体不佳，请立即打电话给我们的护士。

2. If it should rain tomorrow, I will stay at home. 明天下雨我就呆在家里不出去。

3. I don’t think it will happen, but if it should happen what shall we do? 我认为那件事不会发生，但如果真的发生，我们该怎么办?

4. If he should need this instrument, he may use it. 如果他万一需要这个仪器，他可以使用它。

5. If he should fail to do the work, you may ask John to go there in his place. 万一他不能做那工作，你们就叫约翰代替他。

▲ 以上例句均可以去掉if，把条件句倒装：

1. Should you feel worse, please call our nurses at the Triage immediately. 如果您觉得身体不佳，请立即打电话给我们的护士。

2. Should it rain tomorrow, I will stay at home. 明天下雨我就呆在家里不出去。

3. I don’t think it will happen, but should it happen what shall we do? 我认为那件事不会发生，但如果真的发生，我们该怎么办?

4. Should he need this instrument, he may use it. 如果他万一需要这个仪器，他可以使用它。

5. Should he fail to do the work, you may ask John to go there in his place. 万一他不能做那工作，你们就叫约翰代替他。

6. Should you be fired, your health and pension benefits will not be automatically cut off.

如果你被解雇，你的医疗和养老保险金不会自动中断。

7. Should you buy a home from Lovell, the company promises to buy it back at the same price after three years.

如果你从洛弗尔公司买房子，该公司承诺3年后以同样的价格再购回。