A metal surface illuminated by 8.5×1014 Hz light emits electrons whose maximum energy is 0.52 eV. The same surface illuminated by 12.0×1014 Hz light emits electrons whose maximum energy is 1.97 eV. The work function of the metal is ( B )
A metal surface illuminated by 8.5×1014 Hz light emits electrons whose maximum energy is 0.52 eV. The same surface illuminated by 12.0×1014 Hz light emits electrons whose maximum energy is 1.97 eV. The work function of the metal is ( B )
2. Greenhouse gases are the gases absorbs and emits radiant energy within the thermal infrared range, which cause the .
2. Greenhouse gases are the gases absorbs and emits radiant energy within the thermal infrared range, which cause the .
从这种材料中散发出的烟雾对皮肤是有害的。 A: The fumes from this material are dangerous to the skin. B: The vapors that this material emits are dangerous to the skin.
从这种材料中散发出的烟雾对皮肤是有害的。 A: The fumes from this material are dangerous to the skin. B: The vapors that this material emits are dangerous to the skin.
What is the finding of the new study？ A: Quick-cooking microwave ovens have become more popular. B: The frequent use of microwaves may do harm to our health. C: CO₂ emissions constitute a major threat to the environment. D: The use of microwaves emits more CO₂ than people think.
What is the finding of the new study？ A: Quick-cooking microwave ovens have become more popular. B: The frequent use of microwaves may do harm to our health. C: CO₂ emissions constitute a major threat to the environment. D: The use of microwaves emits more CO₂ than people think.
Suppose you are riding on a hot air balloon, carrying a buzzer that emits a sound of frequency f . If you accidentally drop the buzzer over the side while the balloon is rising at constant speed, the frequency and intensity of what you can hear sound as the buzzer falls toward the ground ___________ and __________ respectively. (fill in increases/decreases and use the comma to connect two choices)
Suppose you are riding on a hot air balloon, carrying a buzzer that emits a sound of frequency f . If you accidentally drop the buzzer over the side while the balloon is rising at constant speed, the frequency and intensity of what you can hear sound as the buzzer falls toward the ground ___________ and __________ respectively. (fill in increases/decreases and use the comma to connect two choices)
What is the finding of the new study? A: Quick-cooking microwave ovens have become more popular. B: The frequent use of microwaves may do harm to our health. C: CO2 emissions constitute a major threat to the environment. D: The use of microwaves emits more CO2 than people think.<br/>D选项的排放二氧化碳和原文可以匹配。
What is the finding of the new study? A: Quick-cooking microwave ovens have become more popular. B: The frequent use of microwaves may do harm to our health. C: CO2 emissions constitute a major threat to the environment. D: The use of microwaves emits more CO2 than people think.<br/>D选项的排放二氧化碳和原文可以匹配。
（2019.12-3.2）51.Popping food into the microwave for a couple of minutes may seem utterly harmless, but Europe’s stock of these quick-cooking ovens emit as much carbon as nearly 7 million cars, a new study has found.51. What is the finding of the new study? A: A) Quick-cooking microwave ovens have become more popular. B: B) The frequent use of microwaves may do harm to our health. C: C) CO2 emissions constitute a major threat to the environment. D: D) The use of microwaves emits more CO2 than people think.
（2019.12-3.2）51.Popping food into the microwave for a couple of minutes may seem utterly harmless, but Europe’s stock of these quick-cooking ovens emit as much carbon as nearly 7 million cars, a new study has found.51. What is the finding of the new study? A: A) Quick-cooking microwave ovens have become more popular. B: B) The frequent use of microwaves may do harm to our health. C: C) CO2 emissions constitute a major threat to the environment. D: D) The use of microwaves emits more CO2 than people think.
What is the finding of the new study？ 未知类型：{'label': 'questionDesc', 'content': '请根据材料选择正确答案。', 'isMemberControl': 0, 'type': 181} 未知类型：{'label': 'source', 'content': '2019年12月 四级 卷二 仔细阅读2', 'isMemberControl': 0, 'type': 181} A: Quick-cooking microwave ovens have become more popular. B: The frequent use of microwaves may do harm to our health. C: CO2 emissions constitute a major threat to the environment. D: The use of microwaves emits more CO2 than people think.
What is the finding of the new study？ 未知类型：{'label': 'questionDesc', 'content': '请根据材料选择正确答案。', 'isMemberControl': 0, 'type': 181} 未知类型：{'label': 'source', 'content': '2019年12月 四级 卷二 仔细阅读2', 'isMemberControl': 0, 'type': 181} A: Quick-cooking microwave ovens have become more popular. B: The frequent use of microwaves may do harm to our health. C: CO2 emissions constitute a major threat to the environment. D: The use of microwaves emits more CO2 than people think.