横向
1
Unit of electric potential
3
Center of an atom or cell
5
Magnetic metallic element
8
Force that attracts objects together
9
Path of a planet around the sun
10
Disturbance that transfers energy
纵向
2
Positive particle in nucleus
4
Mass per unit volume
6
The Red Planet
7
Amplified beam of light
11
Smallest unit of an element
12
Gas essential for breathing