问题
选择题
一场篮球赛下来，我们消耗了大量的能量，不仅如此，所有生命活动都需要消耗细胞内的能量，这些能量主要是由（ ）
A．线粒体提供
B．叶绿体提供
C．细胞膜提供
D．细胞核提供
答案
生物体的生命活动需要的能量，来自呼吸作用，呼吸作用的场所是线粒体．呼吸作用是在活细胞中的有机物在氧的参与下被分解成二氧化碳和水并释放出氧气的过程．
故选：A
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一场篮球赛下来，我们消耗了大量的能量，不仅如此，所有生命活动都需要消耗细胞内的能量，这些能量主要是由（ ）
A．线粒体提供
B．叶绿体提供
C．细胞膜提供
D．细胞核提供
生物体的生命活动需要的能量，来自呼吸作用，呼吸作用的场所是线粒体．呼吸作用是在活细胞中的有机物在氧的参与下被分解成二氧化碳和水并释放出氧气的过程．
故选：A
Directions: There are 10 blanks in the following passage. For each numbered blank, there are 4 choices marked A, B, C and D.
| The United States is well-known for its network of major highways designed to help a driver get from one place to another in the shortest possible time. (51) these wide modern roads are generally smooth and well maintained, with (52) sharp curves and many straight sections, a direct route is not always the most (53) one. Large highways often pass by scenic areas and interesting small towns. Furthermore, these highways generally (54) large urban centers which means that they become crowded with heavy traffic during rush hours, (55) the "fast, direct" way becomes a very slow route. However, there is almost always another route to take (56) you are not in a hurry. Not far from the (57) new "super highways", there are often older, less heavily traveled roads which go through the countryside. (58) of these are good two-lane roads; others are uneven roads curling through the country. These secondary routes may go up steep slopes, along high cliffs, or down frightening hillsides to towns (59) in deep valleys. Through these less direct routes, longer and slower, they generally go to place where the air is clean and the scenery is beautiful, and the driver may have a (60) to get a fresh, clean view of the world. |
A．when
B．for
C．but
D．that