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...
...d. 这绝对是我吃过的最糟糕的食物。但我认为这个句子的时态有问题，因为主句与从句的时态自相矛盾，我觉得应作如下改动：It is absolutely the worst food I have ever had. It was absolutely the worst food I had ever had. 但老师说，他的句子也不...