Interviews were carried out ________ over the telephone，via e－mail or fax or face to face in four cities including Beijing，Shanghai，Guangzhou and Wuhan.

 As he works in a remote area, he visits his parents only ____.

He tried his best to solve the problem, _____ difficult it was.

We decided not to climb the mountains as it was raining ________ .

My brother was still studying _______into the night while I was _______asleep.