16.However， unless，there is a good chance17.The author unfairly trivializes

18.Given that， the prediction aboutis still in lack of solid ground.

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

20.The statistics offeredwarrants only the conclusion that

21.Therefore， any decision aimed at addressing the problem ofmust be based on more thorough investigation^{1 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^{2 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 aboutare doubtful