横向
1
Center of an atom or cell
5
Unit of force
6
Mass per unit volume
7
Unit of energy
8
Force that attracts objects together
纵向
2
Our home planet
3
Icy body with a tail near the sun
4
Gas essential for breathing
9
Fourth state of matter
10
Chemical element in table salt
11
Form of thermal energy
12
Preserved remains of ancient life