Recently some scientists have concluded that meteorites found on Earth and long believed to have a Martian origin might actually have been blasted free of Mars’s gravity by the impact on Mars of other meteorites.

　　最近，某些科学家得出结论认为，那些在地球上发现的并一直被相信源自火星的陨石(meteorite)，实际上有可能是由于其它的陨石撞击火星而致使其被震离火星的重力作用范围。

　　难句类型：复杂修饰

　　解释：这个句子难就难在以that引导的宾语从句，从句中的主语是meteorites，修饰它的成分有两个，一个是found on Earth，另一个是long believed to have a Martian origin，两个冻死的成分之间以and 相连接。注意，这里不能把原句理解成是meteorites found on Earth and meteorites long believed to have a Martian origin的省略形式，这个表达是说有两种陨石，一种是地球上发现的，另一种来自于火星，原文所指的是同一批陨石的两个特征，发现于地球，来自于火星。

　　句子最后的by the impact on Mars of other meteorites读上云令人感到不舒服的原因，是the impact of other meteorites中的impact of 被修饰impact的on Mars分隔开了。

　　意群训练：Recently some scientists have concluded that meteorites found on Earth and long believed to have a Martian origin might actually have been blasted free of Mars’s gravity by the impact on Mars of other meteorites.