What were two basic causes of the dust bowl during the early 1930's?

Which best describes why it is necessary to evaluate a solution?

Ialready know the answer to this question but i wanted to ask you guys to see if you know. who started the okinawan karate style ryukyu kempo? when year was it found?

Identify the example of when situation and time are key to assessing risk of harm in a research study: a study on the efficacy of a behavioral intervention for smoking cessation involves both adults and teenagersasking women if they have had an abortionresearch on the prevalence of hiv-infected individuals in communitiesa survey about sexually transmitted diseases