题目

如图所示，F、O分别为凸透镜的焦点和光心，请在下图中画出平行主光轴入射的光线经过凸透镜后的折射光线。 答案：【答案】见解析所示【解析】试题分析：凸透镜有三条特殊光线：过光心的光线其传播方向不变；过焦点的光线经凸透镜折射后折射光线平行于主光轴；平行于主光轴的光线经凸透镜折射后折射光线通过焦点．由图示可知，折射光线线过焦点，根据折射光线的特点，可以画出对应的入射光线。折射光线 阅读理解 　　Bill Clinton took office(就职)on January 20,1993 and became the 42nd U．S．President(总统)．He is the first U．S．president who was born after World War II．He is also one of the youngest of all U．S．presidents． 　　Clinton was born in a poor family．Three months before he was born, his father, William Blats, died．When he was small, his mother remarried(再婚)Norger Clinton, so the boy‘s family name was changed． 　　In the summer of 1963, Clinton was asked to visit the city of Washington．During his visit, he met President Kennedy in the White House．At that time, he wanted to become a president, and now he is! (1) Clinton became the 42nd U．S．president when he was________． [　　] A． thirty B． about forty C． forty-seven D． 37years old (2) Clinton’s father died________． [　　] A． after 1946 B． before Clinton was born C． before World War II D． when Clinton was young (3) Why was the boy‘s name changed? [　　] A． Because he became a president B． Because his family was very poor C． Because his father was dead D． Because his mother remarried Norger Clinton (4) In 1963 Clinton came to the city of Washington________． [　　] A． to take part in an exam B． for his holidays C． for a visit D． to have a meeting with Kennedy (5) Which one of the following is Not right? [　　] A． Everybody can visit the president in the White House B． All the U．S．presidents work in the White Horse C． Clinton wanted to become a president after he saw President Kennedy D． The White House is in the city of Washington