题目内容
显微镜的放大倍数是物镜的放大倍数与目镜的放大倍数的乘积。
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显微镜油镜观察时，将聚光镜上升至最高位置并开足光圈，可以获得最多的光线。
普通光学显微镜一般有3~4个物镜，装在镜筒下端的旋转器上，其中最短的刻有"100×"符号的为油镜。
P156Lead-inTask 1 Listen to an audio clip about carbon footprints and decide whether the following statements are true(T)or false(F).( )1.CO2 will be released into the atmosphere when fossil fuels are burned, contributing to global warming.() 2. Scientific evidence suggests that once we reduce greenhouse gas emission, we will solve the problem of climate change.()3. A carbon footprint refers to the total amount of fuel you burn for energy in one day.()4.You do not leave a carbon footprint if you remain still, for example, when vou watch TV.()5.Carbon footprints vary with the way of measuring.[音频]
P159Lead-inTask 1. Listen to an audio clip about biofuels and decide whether thefollowing statements are true (T)or false(F).() 1. Biofuels are made from biomass.()2. There are two types of biofuels: corn or sugar based ethanol and biodiesel.() 3. It is predicted that biofuels have the potential to meet up to a quarter of world demand for transportation.()4. Biodiesel is used more widely in the US than in Europe.[音频]
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