16.However， unless…，there is a good chance…17.The author unfairly trivializes…

18.Given that…， the prediction about…is still in lack of solid ground.

19.Comprehensive analysis is necessary to identify the actual cause（s） of…

20.The statistics offered…warrants only the conclusion that…

21.Therefore， any decision aimed at addressing the problem of…must be based on more thorough investigation to gather sufficient data insgroupsto narrow down and locate the actual cause（s） of the problem.

22.There is also the possibility that…

23.From the survey quoted in the argument， however， we find no sign of such procedures for random sampling， and have good reason to doubt if the sample is representative enough to reflect…

24.If this will be the case，…not necessarily mean…

25.Without further investigation any claims made about…are doubtful…