单选题：Sarah pretended to be cheerful, ________ nothing about the a..

At the beginning of class, the noise of desks _______ could be heard outside the classroom.[ ]A. opened and closedB. to be opened and closed C. being opened and closedD. to open and close

himself to supporting his brother’s son,he has to let one of his children leave school. [ ]A.Having committed B.Committed C.Being committed D.To commit

Look over there-there's a very long, winding path ________ up to the house. [ ]A. leadingB. leadsC. ledD. to lead

_ that she didn't do a good job, I don't think I am abler than her.[ ]A. To have said B. Having saidC. To sayD. Saying

_____ a written permission, he had to write another letter to the president of the university. [ ]A. Not giving B. Not having been given C. Having not given D. Having not been given