This effect was imperfectly understood by designers at that time.
当时的设计者们没有完全理解这种效果。
...in a country whose language she spoke imperfectly.
在一个她不能完全掌握该国语言的国家里
2N-SING (动词的)未完成过去式,未完成过去时 In grammar, the imperfect or the imperfect tense of a verb is used to describe continuous situations or repeated actions in the past. Examples are 'I was reading' and 'they were eating'. (动词的)未完成过去式,未完成过去时