Victor apologized for ______ to inform me of the change in the plan.[ ]

Someone called you just now.——I know. But I was busy at that moment. When I calledback, there was no.

It was announced that only when the terrible diseasewas under control _____ to return to their homes.

The traditional view is ______ we sleepbecause our brain is “programmed” to make us do so

I wonder ________ you water this kind of flower. —Every other day.