be certain that of

These results provide support for researchers' prediction that naltrexone will turn out to be toxic to certain types of bacteria.

这些结果支持了研究人员的预测，即纳曲酮对某些类型的细菌是有害的。

Scientists say both studies demonstrate that certain parts of the ecosystem respond rapidly to reductions in atmospheric pollution, but that these findings should not be used as a license to pollute.

科学家称这两项研究都表明，生态系统的某些部分对于大气污染的减少反应迅速，但这些发现不应该成为允许污染的理由。

They can just be symptoms of a sleep disorder that can result from an unpleasant experience, stress, or certain drugs.

它们可能只是睡眠障碍的症状，可能是由不愉快的经历、压力或某些药物引起的。