3、earnest指人或举止认真而诚恳的。
4、grave尤指因发生重大或令人担心的事件而神情严肃的。
例句:
1、A lot of drivers have a serious attitude problem.
许多驾车者有严重的态度问题。
2、The most serious cases were treated at the scene of the accident.
受伤最严重的人在事故现场就得到了救治。
3、We've had one or two problems ─ nothing serious.
我们有一些问题,不过没什么大不了的。