ascertain

1. V-T If you ascertain the truth about something, you find out what it is, especially by making a deliberate effort to do so. (尤指經(jīng)過努力) 查明[正式]

Through doing this, the teacher will be able to ascertain the extent to which the child understands what he is reading. 通過這樣做，老師將能確定這個(gè)孩子對(duì)他正在讀的內(nèi)容的理解程度。

Once they had ascertained that he was not a spy, they agreed to release him. 一查明他不是間諜，他們就同意了釋放他。