Hi teachers,<br/><br/>Is "up" necessary in these sentences, or it can be left out? Thanks.<br/><br/>Examples:<br/><br/>1. She called me <b>up</b> at the office.<br/><br/>2. I can't open <b>up</b> the window / disk.<br/><br/>3. This item will sure be snatched <b>up</b> very quickly at the supermarket.<br/><br/>Regards,<br/><br/>Tinanam