1.because 习惯上不与 so 连用。汉语习惯上说“因为…所以…”，但英语习惯上却不能将 so与because 连用：

　　因为下雨，所以我们呆在家里。

　　误：Because it was raining, so we stayed at home.

　　正：Because it was raining, we stayed at home.

　　正：It was raining, so we stayed at home.

　　2.(al)though 习惯上不与 but 连用。汉语中可说“虽然…但是…”， 但按英语习惯，通常不能说although…but?或though…but：

　　虽然很危险，但我要试试。

　　误：Although it is dangerous, but I will try.

　　正：Although it is dangerous, I will try.

　　正：It is dangerous, but I will try.