Question

it is believe that the huge cave was discovered

y accident

Answer 1

该句要表达的意思：据说这个巨大的岩洞是偶然被发现的。
英文表达：It is believed that the huge cave was discovered by accident.
It is said that the huge cave was discovered by accident.
解释：这是由it作形式主语引导的从句。真正的主语是the huge cave was discovered by accident，所以这件事情是被相信的，所以要用被动式。
It is said that 据说 是一个固定搭配
by accident 偶然 是一个固定短语
希望能帮到你。