题目

物体A的加速度为3 ,物体B的加速度为-5 ,下列说法正确的是() A . 物体A的加速度比物体B的加速度大 B . 物体B的速度变化比物体A的速度变化快 C . 物体A的速度一定在增加 D . 物体B的速度可能在减小 答案：B,DAVERAGE RESOURCES620 m3 waterIf we put fresh water and sea water together, we can each have 620 m3 water. But remember, sea water is too salty for us to drink if the factories don’t process it first. So, 620 m3 is little. Saving water in daily use is important.0.5 hectares of forestsThere are 3.869 billion hectares(公顷) of forests on Earth. But we are losing them mainly because we cut trees too much. If we calculate（计算）at the size of a football field, we are losing 343,000 football fields every day, or 1,431 per hour, or 24 per minute!1.5 centimeters long corals(珊瑚)All the corals that we have now spread for about 100,000 km in 109 countries. But each of us can only have such a little piece, because seas are getting polluted and corals are dying.33 starsAccording to the latest report, there are 200 billion stars in the Milky Way. Each of us can have 33 of them. Unfortunately, we cannot see most of the 200 billion stars from Earth. We can only see about 6,000 stars. If we don’t use telescopes or we have bad weathers, we can only see about 2,000 stars.90kg riceOn average, we harvest 0.54 billion tons of rice each year round the world and each of us can have 90 kg. Asia produces and eats 90% of all the rice. How long will it take you to eat up this 90 kg rice?1 icebergLuckily, we still have icebergs to share when Earth gets warmer and warmer. Each of us can have an iceberg of 170m×170m×170m. Up to 10% of Earth surface is covered by ice. There is 31,000,000km3 of ice on Earth in all.小题1:On average we each probably have ________ fresh water in the world.A．over 620m3B．more than 620m3C．far less than 620m3D．only 620m3小题2:We are losing the forests on Earth mainly because of________.A．the man-made damageB．the climate changeC．the construction of many football fieldsD．the environmental pollution小题3:When we don’t use telescopes or the weather is bad, we can see ________ stars from Earth.A．all the stars B．about 2,000C．about 200 billionD．about 6,000小题4:According to the table above, we each can only have _____ because of pollution.A．less water B．fewer icebergs C．fewer corals D．less rice