“convenient sampling”造句，怎麼用convenient sampling造句

By convenient sampling, 30 CHB outpatients from a tertiary A-level hospital in Guangzhou were recruited into this study.

By convenient sampling, 105 stable COPD patients from three hospitals in Beijing were recruited in this study.

The research object of the study is the domestic tourists, and we distribute questionnaires to the college student travelers on campus by convenient sampling.