根据句意,选择下面的疑问词填空how,when,where,what,which26,-Could you tell m

根据句意,选择下面的疑问词填空
how,when,where,what,which
26,-Could you tell me ________to use a computer?
-It's easy.Press the power button first.
27,-I forgot _____________to put the useless file.
-Oh,you can put it in the Recycle Bin
28,-I don't know ________to do next.
-Well,click on the "Start"icon and choose a program in Program Files.
29,-I can't remember _________button to click on.
-You have to click on the left button
30,-Please tell me _________to trun off the power.
-Just when you see the words"You can power off safely."