对中国人来说，倒是分不太清when和while，以为when和while都是表示“当....的时候"

我在上海期间，我想见见我的中国朋友们

While is past, when is present. " 当我在上海的时候，我想遇到我的中国朋友们。The chinese sentence is a statement of the past event. Meaning, while I was in Shanghai, ....... In Chinese, while and when is the same, it depends on the construction of the full sentence. Native Chinese can tell 'while" or "when" by just looking at your statement of fact.

while 和 when 漢語里頭公用 “當。。。的時候” 有時不能完全以母語方式來表達它。這就所謂的各有其特殊之點。

那“趁”呢？“趁在上海希望见面我中国朋友“？