Since… 和完成时态连用。

　　e.g. Since he was born， he has been troubled by frequent colds.

　　考点：考察常见介词的习惯用法。

　　7. D. 分析：借助句子中的相关词语（bomber planes）含义直接判断答案。

　　补充：

　　On： 表示…的状态或过程，表…的意图

　　on leave/休假； on fire/着火； on the way/在途中

　　travel on business商务旅行

　　考点：考察常见动词短语。

　　take up v.拿起， 开始从事， 占据

　　take after v.象， 学样

　　take.。as.。：把。。看作。。

　　Later that day， all communications with Flight 1 9 were lost．They just disappeared without a trace．

　　The next morning，242 planes and 19 ships took part in the largest air-sea search in history． But they found nothing. 8． A)for B) about C) on D) from

　　Some people blame the disappearances__8__supernatural forces．

　　8． C．分析：借助搭配结构 (blame the disappearance.。 supernatural force)判断C是答案。

　　考点：考察常见动词短语。

　　blame 。。(on， upon)。。 把。。。归咎于。。

　　e.g. Dont blame it on him， but on me.别怪他， 该怪我。

　　Blame.。for.。指责。。造成了。。

　　e.g. They blamed the secretary for the delay of the plan.他们怪罪秘书造成计划延误。

　　9．A)missing B) missed C) miss D) having missed