have always regretted ______ harder at school.

His heart racing, and tears ____ his eyes, Jack carefully unlocked the box.

The fast popularity of cloud computing means netizens will need to take added measures to make sure their data stay __________in the digital age.

I called Mary many times yesterday evening, but Icouldn’t get through. Her brother _________ on the phone all the time.

We can’t ______ the carThere ______ something wrong with the engine