4.因为......;由于......

　　because(连词)+从句

　　because of(介词短语)+名词(短语)

　　I didn’t go to school because I had a headache.

　　因为我头疼，所以我没去上学。

　　He was late for class because of the bad weather.

　　由于糟糕的天气，他上课迟到了。

　　注意：because和so不能同时连用。

　　5.来自

　　be from=come from

　　Where are you from?=Where do you come from?

　　你来自哪里?

　　6.How often多久一次(对频率提问)

　　How long多久(对一段时间提问)