It is widely believed that an apple which fell from its branches were the _______ for Newton’s discovery of gravity.
-- We could invite John and Barara to the Friday night party. --Yes, ____? I’ll give them a call right now.
Try ___ she might, Sue couldn’t get the door open.
I’m sorry I didn’t phone you, but I’ve been very busy ___ the past couple of weeks.
The two girls are so alike that strangers find ____ difficult to tell one from the other.
It ___ be the postman at the door. It’s only six o’clock.