标题: OG Verbal蓝皮 SC 8, when 可以用作非限制性定语从句的开头嘛？求解答 [打印本页] 作者: stevenlong 时间: 2011-8-1 17:54 标题: OG Verbal蓝皮 SC 8, when 可以用作非限制性定语从句的开头嘛？求解答 8. As the cost of wireless service has steadily dropped over the last year and as mobile phones have become increasingly common, many people are finding that they can avoid toll charges on their home phones, using their mobile phones for making long-distance calls at night or on weekends, at a time which many wireless companies provide unlimited airtime for a small monthly fee.
(a) phones, using their mobile phones for making long-distance calls at night or on weekends, at a time which (b) phones, instead using mobile phones to make long-distance calls during the night or weekends, during which (c) phones by using their mobile phones to make long-distance calls at night or on weekends, when (d) phones using their mobile phones for make long-distance calls during night or weekends, when (e) phones when using their mobile phones to make long-distance calls at night or weekends, a time which