to slowly move your body into a sitting or lying position, in a relaxed or tired way

I was so tired when I got home that all I wanted to do was sink into bed/an armchair/a hot bath. 我回家后太累了，只想躺在床上／坐到扶手椅里／洗个热水澡。

to spend a large amount of money on a business or other piece of work

We sank all our money into my brother's business. 我们把自己所有的钱都投在了我哥哥的生意上。