物理老师的茶杯静止放在水平桌面上，则 (     )

如图表示信号传导的一种方式．X表示产生信息分子Z的细胞，Y是Z的靶细胞．下列对应关系合理的是（　　）

阅读下面短文，从A、B、C、D四个选项中选出最佳选项。

    David is a good student at school, but he is not clean. His face and hands are often dirty. He washes them with water only. He doesn't like to use soap(肥皂). He has an aunt. His aunt comes to see him. She looks at David and says, " David, I know what you ate for breakfast this morning." "What?" David looks at his aunt and asks.

"Eggs," says his aunt. "Your face and mouth tell me that."

    "You are wrong, my dear aunt!" says David. "Not today or yesterday, but the day before yesterday."

教室里不同位置上的同学都能看到黑板上的粉笔字是 ____，黑板反光是 ____（填“漫反射”或“镜面反射”）。漫反射 ____（填“遵循”或“不遵循）光的反射定律。

对原子核电子以及电子的运动，下列描述不正确的是（　　）