All the lights ______ before we left the office.A.has been turned offB.have turned offC.ha

________ before we depart the day after tomorrow,

________ before we depart the day after tomorrow,

________ before we depart the day after tomorrow,

The teacher required that all the assignments _____finished before this weekend.

______all visible lights, red light has the longest and violet the shortest wavelength.A．A

Before 2010 we will finish _______ the park.A bui