Which of the following is true of clouds at medium altitudes?

a. they are a sign of severe weather.
b. they generally produce lightning.
c. they are made of ice crystals.
d. they cause light rain and snow.

How does water pollution affect the environment

The diagram shows the positions of the sun, moon and earth during spring tides, when the high tides are at their highest and low tides at their lowest. what is it about these positions that causes these high and low tides?

Triangle with the the sides 72 and 75 and x. also other trsingle withsides 24 25 and 7. what is the value of x.