Althoughwarnings are often appropriate and necessary——thedangers of drug interaction, for example—— and many arerequired by state and government, it isn't clear that they actually protect themanufacturers and sellers from liability if a customer is injured.
一眼掃視之后,發現這個句子挺長的,而且有兩個破折號。兩個破折號,或是兩個逗號之間的內容往往是插入語的成分。這種成分的特點就是拎出來之后不影響句子的結構,并且在考研閱讀文章中,這樣的成分又往往不是文中的重點信息,所以應該直接跳過對其采取不予理睬的策略。通過簡化,句子結構及會變得清晰,理解起來也更加容易。