______, he couldn’t get the door open.
Not until World War II ______ to use new chemical techniques to purify penicillin.
--- What did the manager say at yesterday’s meeting? --- So you______ to him carefully.
--- Did Jack come back early last night? --- Yes. It was not yet eight o’clock ______ he arrived home.
In some countries citizens are ______ to vote, and if they don’t they get fined.
We’ve been looking at houses but haven’t found ______ we like yet.