問(wèn)題補(bǔ)充：
單選題
Reports showed that it was not the first time this state-owned firm ________ serious accidents．A.has happenedB.had happenedC.has experiencedD.had experienced
網(wǎng)友答案：
熱心網(wǎng)友 1樓
D解析解析：根據(jù)固定句型It is/was the first time that…h(huán)as/had done sth．判斷，排除A、C；happen為不及物動(dòng)詞，后不接賓語(yǔ)；experience（經(jīng)歷）為及物動(dòng)詞，后接賓語(yǔ)。故選D．
