Since it will take years to know the effect of genetically modified food it’s more sensib

问题补充：

Since it will take years to know the effect of genetically modified food, it’s more sensible to give it a second thought before we eat it,it?

A. isn’t

B. is

C. won’t

D. will

答案：

(答案→)A. isn’t

B. is

C. won’t

D. will

解析：句意：既然花费了几年的时间已经知道转基因食物的影响了，那么在吃它们之前需思考一下是更明智的是吗？这是反意疑问句，它的后半部分与主句的主语及谓语保持一致，因为前面是肯定的，所以后面用否定的，故选A。