QHas he turned on the computer yet?
AYes, he has./No, he hasn't.
QHas she already printed the photos?
AYes, she has./No, she hasn't.
QHas she uploaded the photos yet?
AYes, she's uploaded them./No, she haven't.
QHas he written the email yet?
AYes, he has./No, he hasn't.
QHas she logged out of the website yet?
AYes, she has./No, she hasn't.
QWhat have scientists designed to use wind energy?
AScientists have designed wind turbines that make electricity.
QWhat have scientists designed to use solar energy?
AScientists have designed solar panels and dams that make electricity.