—What does this sign mean, Miss Chen?—Oh, it says that we ________take photos here.A. needn’t B. may not C. mustn’t
Mark is telling his parents _____ he saw on the way home just now.
She has some trouble _____ out the math problem.
You have to adapt_____ the new environment when you go to a new place.
I want to know _____.
Both Mark and Jim _____ very hard. They are top students.