since then后面加什么时态?
Eg.
Scientists __________ (build) a station at the South Pole several yearsago.Since then they
________________ (get) muchinformation about the South Pole.怎么填?
人气：318 ℃ 时间：2019-09-06 03:48:00
解答
用built,表示过去式,several years ago是明显的过去时标志；
用have got,表示过去完成时,Since then作为标志!
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