The problem is that the compound has mixed effects in the brain, a not unusual occurrence with psychoactive drugs.

问题在于，这种化合物对大脑有混合作用，这种情况在服用精神药物时并不少见。

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Messages have variable data for each instance or occurrence of the element to identify the precise resource and other data required to fix the problem.

消息具有用于元素的每个实例或每次出现的变量数据，以标识修复问题所需的精确资源和其他数据。

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The Nosema ceranae fungus can sicken bees when they ingest spores, and Cramer explains that the occurrence of both the iridescent virus and the fungus at the same time seems to be the problem.

这种东方蜜蜂微孢子虫在吸收孢子的时候就会导致蜜蜂生病，克莱默还解释说昆虫虹彩病毒和合真菌的同时出现可能是问题的所在。

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It's a common occurrence and not indicative of a problem, though it can appear more severe in some vehicles depending on how they are used, the design of their exhaust systems and other factors.

WSJ: How to Keep a Deer Out of the Headlights

"I had the problem a few years ago at the 2002 Commonwealth Games and never thought there would be a re-occurrence, " Pavey explained.

BBC: Jo Pavey receives assistance after the Great North Run