我找到两种说法,一是时态不变,例句:Scientists discovered that DNA holds the code for life.一是时态可变可不变,例句Copernicus proved that the earth goes/went round the sun.请问如何理解这两个句子?
Many of the reductions over the past 30 years have been achieved either
by reducing the amount of sugar, salt or fat in a product, or by finding
an alternative ingredient.这个句子have been achieved是什么时态
The list included most of the things Hugh loves: butter, potatoes, rice, beer, milk, chocolate,and sweets. 如果主句是一般过去时态,从句常用过去的某种时态;这里时态为什么不一致?为什么用loves而不是用过去时?
...我想问一下:这样的having done 形式的分词作状语,主句的时态是什么时态?Having gone through a phase of racial discrimination,the United States
of American today recognizes four races in the country.这句话为什么是recognizes 而不是recognized? 第二个句子:The mo...