请生成题目中描述生成对应的视频---**Extracted Content:** **Question Stem:** 12. 如图，在科学《光的反射》活动课中，小明同学将支架平面镜放置在水平桌面 MN 上，镜面 AB 的调节角（∠ABM）的调节范围为 12°~70°，激光笔发出的光束 DC 射到平面镜上，若激光笔与水平天花板（直线 EF）的夹角∠EPC=30°，则反射光束 CH 与天花板所形成角的度数不可能取到的为 **Options:** A. 20° B. 50° C. 70° D. 120° **Diagram Description:** * **Type:** Geometric diagram illustrating light reflection. * **Elements:** * **Lines:** * Horizontal line MN labeled "水平桌面" (Horizontal Table). It has a textured surface pattern. * Line AB represents the mirror surface labeled "镜面" (Mirror surface). It is placed on the horizontal table. * Line DC represents the incident laser beam, starting from point D and hitting the mirror at point C. The line segment DC has a thicker end near D, indicating the source. * Line CH represents the reflected laser beam, starting from point C and extending upwards towards H. * Horizontal line EF labeled "天花板" (Ceiling). It is parallel to the horizontal table MN and has a textured surface pattern. * Line EP represents the laser beam path before hitting the mirror or some reference line related to the laser pen position. It connects point E on the ceiling line to point P. * Line PC is part of the incident beam or a projection. * A dashed line CD is shown. * **Points:** * Points M, N on the horizontal table line. * Points A, B define the mirror surface. A is above C, B is below A. C is a point on the mirror surface AB where the incident beam hits. * Point D is the source of the incident beam DC. * Point H is a point on the reflected beam CH. * Points E, F on the ceiling line. * Point P is a point on the ceiling line EF. * **Angles:** * ∠ABM: The angle between the mirror surface AB and the horizontal table MN. It is labeled as the "调节角" (Adjustment angle). Its range is given as 12°~70°. * ∠EPC: The angle between the line EP (related to the laser pen) and the ceiling EF. It is given as 30°. The text clarifies EP is "激光笔与水平天花板 (直线 EF) 的夹角". * ∠PHC: The angle between the reflected beam CH and the ceiling EF. This is the angle whose possible values are asked about. * **Labels and Annotations:** * "水平桌面" (Horizontal Table) next to line MN. * "镜面" (Mirror surface) next to line AB. * "天花板" (Ceiling) next to line EF. * Arrows on lines DC and CH indicate the direction of light propagation. * Labels for points A, B, C, D, E, F, H, M, N, P. * **Relative Position:** The mirror AB is placed on the horizontal table MN. The ceiling EF is above the mirror and parallel to the table. The incident beam DC hits the mirror at C. The reflected beam is CH. Point P is on the ceiling EF, and point C is on the mirror AB. The angle ∠EPC is related to the laser pen's position relative to the ceiling. The question asks about the angle ∠PHC, which is the angle between the reflected beam CH and the ceiling EF. Assuming the ceiling EF and table MN are horizontal and parallel, the angle between the reflected beam CH and the horizontal table MN is also ∠PHC. **Other Relevant Text:** * Activity topic: 《光的反射》 (Reflection of Light) * Person involved: 小明同学 (Student Xiao Ming) * Mirror placed on horizontal table MN. * Mirror surface AB adjustment angle (∠ABM) range: 12°~70°. * Incident laser beam DC hits the mirror surface. * Angle between laser pen and horizontal ceiling (line EF), ∠EPC = 30°. * Question asks for the impossible value of the angle formed by the reflected beam CH and the ceiling (∠PHC).