The poison produced by the spider's skin is so______that it will paralyze a bird or a monkey immediately.
【正确答案】 A
【答案解析】各项的意思是：lethal致死的，有害的； liable有法律责任的，易受……之害的；tedious乏味的，单调的；profound知识渊博的，见解深刻的。根据句意判断，答案是A。