【简答题】小题1:Trees can get light from in the daytime. A.C0 2 B.O 2 C.the sun D.the moon 小题2:Chlorophyll is in . A.sunlight B.soil C.air D.leaves 小题3:We can get more O 2 by . A.planting more trees B.cutting tr...
【单选题】Diffusion of light in the sky occurs owing to ______.
A.
atmospheric impurities
C.
varied shades of colour
D.
different times of the day
【单选题】Rich as they were in forms, the speaker’s _____ seemed unrelated to his speech.
【单选题】触电事故表明,频率为( )Hz的电流最危险。
【单选题】Rich as they were in forms, the speaker’ s _____ seemed unrelated to his speech.
【单选题】Unexpectedly the light ______ and we were left in darkness.
【单选题】直到什么事件的前一天美国参战的前一天,罗斯福才决定要扩大投资规模,从事原子弹的试制计划
【单选题】I can't see anything in the room. Please the light. [ ]
【判断题】触电事故表明,频率为50-100Hz的电流最危险。