How do scientists know that the universe is expanding?
1. The Doppler effect shows stars with yellow shifted light
2. The Doppler effect shows stars with green shifted light
3.The Doppler effect shows stars with blue shifted light
4. The Doppler effect shows stars with red shifted light
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Ahill is made of rock particles of different sizes. which of these agents of erosion probably causes the hill to form? a- waves b- glacial ice c- wind d- flowing water

Ships can transit between the atlantic and pacific oceans using the canal.

Which statements about wells are true? check all that apply. a) wells bring groundwater from the unsaturated zone to the surface of the water. b) wells need to be drilled below the water table. c) if water is pumped from a well too quicky, the well may run dry. d) water from wells is generally not safe to drink. e) water gushes from artesian wells due to pressure.