市场调查的实验调查法是指从影响调查问题的诸多因素中选出一个或两个因素，将它们置于()下进行小规模的实验，然后对实验结果做出分析，研究是否值得大规模推广。
一定条件
暂无解析
Thethreementriedmanytimestosneakacrosstheborderintotheneighboringcountry_____bythepoliceeachtime.
Themotheralmost____whenshelearnedthathersonwasshotdead.
Thebackgardenofourhousecontainsalawn，（）verypleasanttositoninsummer.
Itwasrecommendedthatpassengers_____smokeduringtheflight.
Josephwasverylucky（）withhislife;healmostdidnotgetoutoftheroom.
