Much research _______ into the possible causes of the disease in the past few years.　 (A) has been done (B) was done (C) have been done (D) were done

Much research _______ into the possible causes of the disease in the past few years.　
(A) has been done
(B) was done
(C) have been done
(D) were done

出自：南阳师范学院-教育学-大学英语（四）

提示：
同一【IP】的非会员用户每天可免费获取10次答案

收藏本站【zk.995w.com】，下次访问不迷路

本站试题总数:【10245403】个 (题库试题定时更新)