His success was because of ________ he had been working hard.
----Will Mr. Smith join us in the party ? ----He would, but he _____not . He sometimes likes to stay alone. A must B can C need D may
The notice ______ “No smoking”. A is told B reads C tells D is read
The doorbell had been ringing for several minutes before it ______. A answered B had answered C was answering D was answered
The box _____. Better call in a mechanic(修理工). A isn’t open B hasn’t been open C isn’t be open D won’t open
The workers _____busily when the boss came to look for something she ______in the office. A had worked, had left B were working ; had left C working ; had left D had worked; left