英语四级关键英语语法知识:原因状语从句 较为:because, since, as和for
1)because语势强,用于表明人所不知道的缘故,回应why明确提出的难题。当缘故是不言而喻的或无已大家孰知,就用as或 since。 I didn't go, because I was afraid. Since /As the weather is so bad, we have to delay our journey.
2)由because正确引导的从句假如放到句末,且前边有逗 号,则可以用for来替代。但要不是表明根本原因,只是多种多样状况多方面推论,就只有用for。 He is absent today, because / for he is ill. He must be ill, for he is absent today.