关于凸透镜成像及应用，下列说法正确的是（ ）
A．实像是光线折射形成的，虚像是光的反射形成的
B．像的大小是由物体的大小决定的
C．照相机是利用物体在二倍焦距以外成缩小实像的原理
D．电影屏幕上的像是正立放大的虚像
A、凸透镜成像时，实像和虚像都是光的折射形成的．不符合题意．
B、凸透镜成像时，像的大小取决于物体到凸透镜的距离．不符合题意．
C、照相机是利用凸透镜在二倍焦距以外成倒立、缩小的实像工作的．符合题意．
D、电影屏幕相当于凸透镜实验中的光屏，光屏上能承接到的像都是实像．不符合题意．
故选C．
On a sunny morning, the two men started for the top of Mount Qomolangma. After they climbed over one of the most 69 slopes, they found a man lying in the snow. “He’s going to 70,”Peter looked at John and said, as if he would help the man. “Leave him by himself and just follow me !If you bring the burden with you , I’m 71 you’ll lose your life.”John warned Peter . Then he turned around and walked forward 72. It was too cold. After thinking for a 73 , Peter made up his mind to help the dying man. He carried the man on his back and made his way forward . Little by little , Peter’s temperature made the man74. The man came to himself! And soon he could move all by himself. Together they moved side by side. About two hours later, they kept up with John.To his surprise , they found that John was almost dead in he snow. He had been 75 to death. |