Ratione soli

Their complaints are well-founded.

他们的抱怨是有理由的。

he is justifiably bitter.

他的怨恨是有理由的。

In the young there is a justification for this feeling.

在年轻人中有这种感觉是有理由的。

He had a legitimate reason for being late.

他迟到有合理的理由。

The wolf finds reason for taking the lamb .

叼羊的狼总有理由。

You have given him cause for anger

你使他有发火的理由。

She gave no reason for her absence

她没有说缺席的理由。

Both sides have some justice in their claims.

双方的要求都有些理由。

I have no reason to quarrel with him.

我没有跟他口角的理由。

unwarrantable criticism.

没有充分理由的批评

He has good reason to refuse.

他有充分的理由拒绝。

There were strong reasons for this.

这样做是有充分理由的。

owe a person a grudge

(有正当的理由) 怀恨某人

There are three reasons against it : First...

有三个反对的理由： 第一…

You have no grounds for complaint/for complaining.

你没有抱怨的理由.

There is no real reason for complaint.

没有什么可抱怨的理由。

in an uncalled-for manner.

以没有正当理由的方式。

To have a cause for complaint

有提出抗议的正当理由