横向
1
Gas essential for breathing
4
Substance with pH below 7
6
Tissue that contracts for movement
8
Our home planet
9
Fourth state of matter
12
Positive particle in nucleus
13
Center of an atom or cell
纵向
2
Precious yellow metallic element
3
Curved glass that refracts light
5
Form of thermal energy
7
Blocking of light by a celestial body
10
Mass per unit volume
11
Force that attracts objects together