He commanded that the students ______ the classroom before he returned.

The students discussed the experiment that they would like to see ____ next year.

try to understand ________ that prevents so many children from being happy, there seem to be three causes.

Sales director is a position ________ communication ability is just as important as sales skills.(2012·重庆)

h, ______ he have all these letters typed for you right away —He ______ Theyshould be ready by 10 o’clock this morning