Come加S的用法

They come from France中的Come 如果把They换成Tom and Jane时，Come应该怎么变化，要不要加S呢？刚学英语不太懂，请求指教。

经常问：主语(subject)是一人或多于一人:
1. They come from France. (不要加S)
2. Tom and Jane come from England. (不要加S)
3. Tom comes from England. (单数要加S)
4. He/She comes from Beijing.(单数要加S)
5. My cat is fat. It knows how to come back home every evening.(单数要加S)
*除了第一人单数(我) : I come from Beijing. (不要加S)
**多看你将会明白! Good luck.

必须加s。都是一般现在时态。