1.当身体对进入的特定的物质抵触的时候,就会导致一种敏感症的出现了.
2.an allergy主句主语 results主句谓语动词 when the body reacts adversely to certain substances introduced to it时间状语从句
3.when引导词 the body主语 reacts谓语动词 adversely状语 to certain substances introduced to it状语
4. introduced to it是过去分词短语,作 certain substances的定语,表示被动和完成意义.
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