Supposition 假设论证

　　标志词 provided that…(如果) given the choice…(如果可以选择的话…)only if…(只有…)as long as…(只要) if…, suppose that…

　　e.g. Provided that we can minimize the pain of test animals, animal experimentation should be continued.

　　e.g. Given the choice, many people would live in big cities rather than the countryside.