Why do we tallk about radio waves as a group and not the frequeny of radio waves

Janelle made a hypothesis bout the uneven temperatures inside her house during winter. she believes that 50% of the ducts are blocked and she plans to investigate. if she wants to prove her hypothesis using scientific processes what should she do next?

Several mountains together form a mountain . a few of these combined form a mountain system. several systems combined form a mountain , which can stretch thousands of miles in length.

Notice how they put future which of the clouds shown would indicate a possible future rain storm? a) b) c) d)