used before or after a statement to show that you have thought about the conditions that affect a situation before making a decision or a statement在这种情况下；既然如此
Under the circumstances, it seemed better not to tell him about the accident.在这种情况下，不告诉他有关这次事故的情况似乎更好。
She did the job very well in the circumstances.她在那种情况下仍把工作干得很出色。
In the circumstances, you'd better call the police.在这种情况下，你最好打电话报警。