earnest : 指严肃、认真，含诚恳和热情意味。
- He was a very earnest young man.
- Despite her earnest efforts, she could not find a job.
serious : 指具有关键、严肃或严重意义的事情。
- Please don't laugh - I'm being serious.
- He was wearing a very serious expression and I knew something was wrong.
- On the surface it's a very funny novel but it does have a more serious underlying theme.
grave : 侧重严肃和尊严，需要认真思考，含令人担忧意味。
- a grave situation
- He looked very grave as he entered the room.
severe : 指面孔的严肃，法律的严厉，伤病的严重。着重严厉性，无丝毫温情。
- The headteacher spoke in a severe voice.
- The president is currently facing severe criticism.
- There are severe penalties for failing to declare all your income to the Inland Revenue.
solemn : 指人表情或场景气氛严肃，侧重威严名印象深刻。
- a solemn face/voice
- solemn music
- Everyone looked very solemn.
sober : 侧重因控制或抑制自己的感情而表现出的庄重。
- In fact the whole wedding was a sober affair - no dancing, just people standing around in groups chatting politely.
- Anthony was in a very sober mood - I scarcely heard him laugh all night.