Research has _____ our understanding of the virus.

_____ means to design or create something that has never existed before.

_____ means to add an attachment (= computer file) to an email message.

_____ means to connect a computer to a system of computers by typing your name and often a password, usually so that you can start working.

Training to be a doctor _____ a lot of hard work.

_____ means to stop a computer being connected to a computer system, usually when you want to stop working.

They came to California hoping _____ gold.