—Who______ it be that is knocking at the door? —It ______ be Father, but I’m not sure.
The new supermarket was once close to closing down. But since the underground was opened, business has been _______.
– Where did you find the wallet I lost yesterday?-- It was on the playground ______ we played basketball.
__________ in a new country, I was scared and feeling pretty anxious.
It’s standard practice for a company like this one______ a security officer.
Some of my workmates prefer to send to our QQ group ______ news they’ve got.