They are not all accounted for有的已經失蹤不知去向

account for:報賬;說明(原因等)； 對 ... 負責

He could not account for his absence from school.

他無法說明他曠課的原因。

He'll have to account for where every cent goes.

他得說明所花掉的每一分錢的用途。

He has been asked to account for his conduct.

他被要求解釋他的行為。

account的用法:

1.on his own account和of his own accord不可混用，前者意為“為了自己的利益地，自己負責地”，后者意為“自愿地，自發地”；

2.on account of，意為“因為”，現比較少用upon去替代on；

3.account后可接賓語和表語，且在賓語后偶爾會加上to be,偶爾會加上as，但都不常用。

I account him wise.

I account him a wise man.

注意句子On no account（決不）should we neglect our work中用的是should we,不是we should。

常用短語:

on account記帳

on no account決不

You know of what I speak,你知道我在說的是什么嗎?

know of:知道, 聽說

Do you know of any restaurants open now?

你知道現在那里還有餐廳是營業的嗎？

I don't know of anything to prevent you from doing so.

我不知道有什么能阻止你這樣做。