同学你好，该知识点来自沪江网校《雅思语法精讲【随到随学班】》的课程，想要更系统的学习，欢迎进入课程学习。不仅可以和更多的同学一起学习，而且还有老师、助教随时的学习指导和知识点解答哦。

同学你好~
“we didn't learn an important person on the board until we disembarked.” 这句话存在语法错误，正确的表达应该是 “we didn't learn that there was an important person on board until we disembarked.” ，这里需要用 “that” 引导宾语从句，并且 “on board” 中间不需要加 “the”。
“Because the police had been told that a bomb had been planted in the plane.” 这部分不是一个完整的句子，“Because” 引导的原因状语从句不能单独成句，可将其与前一句合并，如 “we didn't learn that there was an important person on board until we disembarked because the police had been told that a bomb had been planted in the plane.”
“The plane was searched thoroughly, however, the plane found nothing.” 中，the plane found nothing中the plane不可以做主语，应该是人found nothing或是被动语态 nothing was found.
希望对同学有帮助~