题目

Doing your homework is a sure way to improve your test scores, and this is especially true ____ it comes to classroom tests. A. before    B. since      C. when         D. after 答案：C下列各组中的两种固态物质熔化（或升华）时，克服的微粒间相互作用力属于同种类型的是（    ） A.碘和碘化钠                                       B.金刚石和重晶石C.冰醋酸和硬脂酸甘油酯                        D.干冰和二氧化硅