【问】 章振邦等编《新编英语语法》(下)(P.696)在讲限制性关系分句时举了一个正面例句：

The reason why I was alone in the mountains is because I had a difficulty with my guide.

请问这个例句是否正确?

【答】 语言学家们认为The reason is because犯了语义重复的毛病，是应当避免的。例如，CGEL(§15.46)把下列句子看作是典型错误：

The reason (that) they didn’t go to see the house is because they prefer to live in an apartment.

他们没去看房子的原因是他们宁可住在公寓里。

并指出，只有把because改为that，上面的句子才是可以接受的。

F.T.Wood则用下列句子来说明The reason is because是一种常犯的语言错误：

The reason for the delay is because we have had difficulty in obtaining materials.

耽搁的原因是因为我们在获取原材料方面遇到了困难。

并建议改为The delay has arisen because...