雅思作文里的一个句子Inthisgraph,wecanseethatpurchasesoftelevisionswentupin1996andcontinuedtorisesteadilyuntil1998whentheydroppedagainslightly.我对句子后半句有疑问：until1998whenthey……untilwhen

Question

雅思作文里的一个句子
In this graph ,we can see that purchases of televisions went up in 1996 and continued to rise steadily until 1998 when they dropped again slightly .
我对句子后半句有疑问：until 1998 when they …… until when 感觉没有这种说法呢?

Answer 1

until when 不是个结构,只是情境需要.是说直到1998年,然后这个1998后面的when是补充说明1998年发生了什么事,when they dropped again slightly是1998的同位语.