Infinitives and gerunds for uses and purposes

My sister's car has a built-in GPS system. (She use / get directions)

I love my new smartphone. (I use / take pictures)

That's a flash drive. (You use / back up files)

My little brother wants his own laptop. (He would only use / watch movies and play games)

I'm often on my computer all day long. ( I use / shop online and do research)