1. Open Important box need second password but if you have not set that is null. �����е���Ҫ��Ҫ�ڶ������룬�������û���趨������Ч�ġ�
2. The null must intersect with the emitter at the point where you want to emit particles. ������������ͷ������н���ĵ��Ա��ڴ���Щ��λ�������ӡ�
3. The self-calibration scheme can also be extended to null system offset and gain errors in the input channel. �Զ�У����Ҳ���Ա���չ����Уϵͳ���ƫ�ú�����ͨ���е�������
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n.
1. a quantity of no importance
2. lacking any legal or binding force