One possibility is that, deprived of their favourite drug for a day, heavy users suffer withdrawal symptoms or become so grumpy and distracted that they do badly in tests.

• 一种可能性是，断绝喜爱的毒品一天后，服用量大的人出现了停药症状或是变得暴戾。烦乱，从而导致他们在测试中表现糟糕。