所谓“增设”指的是在解题过程中有目的地增加题中非已知的条件,是主动加强命题的一种有效做法,但这种增设是不能改变题意的,否则是无效的.1“P或Q”形式的命题中的“非此即彼”增设形如“P或Q”这种形式的命题为真,即P真或Q真.意思是(1)P真则P或Q真;(2)若P不真,但Q为真,那么P The so-called “additional” refers to the fact that the conditions for the problem of China-Africa are purposefully increased during the process of problem-solving, which is an effective way to take the initiative to enhance the proposition. However, this extension can not change the meaning of the problem or is ineffective. The proposition of the form “P or Q” in the proposition “P or Q” in the form of “P or Q” is true, namely P or Q. This means that (1) P is true P or Q true; (2) if P is not true, but Q is true, then P