─ Mary, who _______ you _______ on the phone─ It’s my best friend, Ann.

No doubt listening to what the teacher says carefully in class ____ less work later. [ ]

Experiments of this kind ________ in both the U. S. and Europe well before the Second World War.[ ]

Please make sure that no details _____ before youdeliver a speech.

Before starting the race, he gave me a ________ look.