So far no life has been found outside the earth, but while some scientists are actively searching for living things in outer space, others firmly believe there ____ . 

Thank you for giving me a hand. I ______ in the experiment without your valuable help. 

___ for the fact that you were lazy, you could have finished the assignment by now. 

―How come I didn’t get the message that we were to have the meeting at 4 pm? ―Well, your phone ________ it．

 The headmaster demanded all the teachers ______ in the office.