“苦难十四年，日本和汉 * * ，压迫老百姓，有苦不能言。”这一历史现象曾经发生在[ ]

下列反应中，属于氧化还原反应同时又是吸热反应的是 [ ]

A．Ba(OH)₂·8H₂O与NH₄Cl反应

B．铝与稀盐酸反应

C．灼热的炭与CO₂反应

D．甲烷与O₂的燃烧反应

伤口边缘整齐，呈线状、出血多、周围组织损伤轻的是

A．刺伤
B．裂伤
C．切伤
D．挫伤
E．皮肤撕脱伤

(A)

Around the world more people are taking part in dangerous sports and activities. Now, there are people who look for an immediate excitement from a risky activity which may only last a few minutes or even seconds.

I would consider bungee jumping (蹦极) to be a good example of such an activity. You jump from a high place 200 meters above the ground with an elastic (弹性的) rope tied to your feet. You fall at up to 150 kilometers an hour until the rope stops you from hitting the ground. It is said that about 2 million people around the world have now tried bungee jumping. Other activities which most people would say are as risky as bungee jumping include jumping from tall buildings and diving into the sea from the top of high cliffs.

Why do people take part in such activities as these Some psychologists suggest that it is because life in modem societies has become safe and boring. Not very 10ng ago, people’s lives were constantly in danger. They had to go out and hunt for food, diseases could not easily be cured, and life was a continuous battle for survival.

Nowadays, according to many people, life offers little excitement. They live and work in quite safe conditions: they buy food in shops, and there are doctors and hospitals to look after them if they become ill. The answer for some of these people is to look for danger in activities such as bungee jumping.

The best title for the passage is（）。

A. Dangerous Sports: What and Why

B. Boredom of Modern Life

C. Bungee Jumping: Is It Really Dangerous

D. Need for Exercise

优质碳素结构钢指含碳量为（）。

A.小于0.3％

B.小于0.8％

C.0.8％～2.3％

D.大于2.3％

A、B两个物体在同一直线上做匀变速直线运动，其速度—时间图象如图所示，则（）

A.A、B两物体运动方向相反

B.4s内A、B两物体的位移相同

C.4s时A、B两物体的速度相同

D.A物体的加速度比B物体的加速度小