has not been, have not been, had not been; would be, would have
分类: 英语语法(00831)发布时间: 2024-08-22 09:55浏览量: 1
has not been, have not been, had not been; would be, would have been, will be If printing____invented, we would not have books and civilization____thousands of years behind. 【正确答案】：had not been, would be