单项选择题
A long line of traffic had to wait at the ______ until the train had passed.
单项选择题 It was not until he entered the classroom ______ he realized that he had forgotten to do the homework.
单项选择题 As the clouds drifted away an even higher peak became ______ to the climbers.
单项选择题 Mary is a conscientious student; she works very hard and is ______ to her teachers.
