He found it hard for Alan to focus on his teachers for longer than five minutes, _________ if the lecture was boring.
As time _____, she became more and more anxious about her son’s safety.
--- It was not until she had arrived home _________ her appointment with the doctor.
The father as well as his three children________ skating on the frozen river every Sunday afternoon.
My sister______ the League last month and she has decided to ______ the activity to help the aged next week.
Eric received training in computer for one year, _______ he found a job in a big company.