2、个从句都缺乏宾语,可见两个引导词都必须充当从句的宾语,所以答案为A项。在下面的例句中,that不充当任何成分,只起语法连接作用(因为句子本身不缺成分):ThattheformerIraqpresidentSaddamwascapturedhasbeenproved.二、引导词whether和if的区别通常,引导主语从句、表语从句和同位语从句时,连词要用whether,而不用if;习惯上也只能说whetherornot,而不说ifornot.例如:_________themeetingwillbeheldinBeijingisnotknownyet.A.WheneverB.If C.