To help students understand how we see, teachers often draw a(n) ________ between an eye and a camera.
句意：为了帮助学生理解我们是怎样看东西的，老师将眼睛和相机作了类比。analogy类比。 contrast对比；差别。image影像；想象。substitute代用品；代替者。因此，本题的正确答案为B。