It's not yet clear whether his resignation offer is a serious one, or whether it's simply a tactical move.

还不清楚他的辞职请求是认真的，还是只是个策略上的举动。

《柯林斯英汉双解大词典》

But his point is a serious one.

不过，他的观点的确很重要。

youdao

Fixing a trivial issue at the cost of a serious one is not good for anyone.

用修复严重问题的代价去修复一个小问题对谁都没好处。

youdao

The study found that one in five children over age two had a low risk of serious injury but received CT scans anyway.

VOA: special.2009.10.28

When he laughed, was witty, in a merry humor, one could scarce sees his eyes, and by and by, when he was serious and positive, he opened his eyes round.

当他笑时，他是睿智的，带有令人愉快的幽默，都看不见他的眼睛了，不一会儿，他变得严肃和积极了，便圆睁着眼睛。

耶鲁公开课 - 政治哲学导论课程节选

One of his early hits in Jamaica, "Serious Times", had a political message.

VOA: special.2010.08.11

They too tend to suggest that there's less chance of an accident, especially a serious one, in heavy traffic.

BBC: Crashes

Not only is the crime of which he is accused a serious one, but the consequences of a conviction are severe.

CNN: Can Kobe Bryant be convicted on 'he said/she said' evidence alone?

One is former DeKalb County Commissioner Hank Johnson, who is black and whose candidacy is being treated as a serious one.

NPR: Ethics Woes for Democrats; God Loses in Nebraska