题目

— The boys are not doing a good job at all, are they?   — _______ . A. I guess not so   B. I don't guess    C. I don't guess so    D. I guess not   答案：D否定回答时，常用I hope / guess not.结构。小孔成像的原理是光的    ．若光源是条形的，小孔是三角形的，则成的像是    形的．