2. I have a serious disturbance on board. ���ڴ�����һ�����صĶ��ҡ�
3. This is a serious book , not an entertainment. ����һ��������飬���ǹ���Dz�ġ�
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adj.
1. concerned with work or important matters rather than play or trivialities
2. of great consequence
3. causing fear or anxiety by threatening great harm
4. appealing to the mind
5. completely lacking in playfulness
6. requiring effort or concentration; complex and not easy to answer or solve