问题
选择题
彩色电视机的屏幕上呈现的各种色彩是由三种色光混合组成的，这三种色光是（ ）
A．红、黄、绿
B．红、黄、蓝
C．红、白、蓝
D．红、绿、蓝
答案
电视荧光屏上丰富的色彩由红绿蓝三原色光混合而成的．彩色电视机荧屏上呈现各种颜色是由红绿蓝三色色光合成的．故ABC错误．
故选D．
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彩色电视机的屏幕上呈现的各种色彩是由三种色光混合组成的，这三种色光是（ ）
A．红、黄、绿
B．红、黄、蓝
C．红、白、蓝
D．红、绿、蓝
电视荧光屏上丰富的色彩由红绿蓝三原色光混合而成的．彩色电视机荧屏上呈现各种颜色是由红绿蓝三色色光合成的．故ABC错误．
故选D．
| 阅读理解。 |
| Six people were travelling in a compartment (车厢) on a train. Five of them were quiet and polite but the sixth was a rude (粗鲁) young man. He was always making a lot of trouble. At last this young man got out at a station with two heavy bags. None of the other travelers helped him but one of them waited the rude young man was very far away. And then opened the window and shouded to him "You left something behind in the compartment." then he closed the window again. The young man turned around and hurried back with his two bags. He was very tired when he arried but he shouted through the window "What did I leave behind?" As the train began to move again, the traveler opened the window and said, "A very bad impression (印象)." |
| 1. The young man was _______ in the compartment to get off the train. |
[ ] |
| A. the first B. the second C. the third D. the last |
| 2. One of the travelers _______ before he was very far away. |
[ ] |
| A. had shouted to the young man B. didn't shout to the young man C. opened the window D. closed the window |
| 3. The other travelers in the compartment _______ the young man. |
[ ] |
| A. were friendly B. were not friendly to C. were pleased with D. were surprised at |
| 4. The young man had _______ with him. |
[ ] |
| A. more than two bags B. just two bags C. two bags and something else D. two more bags. |
| 5. The young man returned _______. |
[ ] |
| A. just before the train moved again B. as soon as the train moved C. just after the train moved again D. when the train began to move |