语法与词汇 31.It is still not clear what______a series of argument between them.
【正确答案】 D
【答案解析】本题空格处是说引发系列的争论。D项“triggered引发,触发”符合题意。如:a high level meeting that triggered bitter bureaucratic debates.(个引发了激烈的官僚政治论争的高级会议。)其他三项“contributed捐献;marked标记;ignited点火,使激动”都不正确。