Q3:

Because of wireless service costs plummeting in the last year, and as mobile phones are increasingly common, many people now using their mobile phones to make calls across a wide region at night and on weekends, when numerous wireless companies provide unlimited airtime for a relatively small monthly fee.

1. Because of wireless service costs plummeting in the last year, and as mobile phones are increasingly common, many people

2. As the cost of wireless service plummeted in the last year and as mobile phones became increasingly common, many people

3. In the last year, with the cost of wireless service plummeting, and mobile phones have become increasingly common, there are many people

4. With the cost of wireless service plummeting in the last year and mobile phones becoming increasingly common, many people are

5. While the cost of wireless service has plummeted in the last year and mobile phones are increasingly common, many people are

d和e区别在哪里,为什么d是正确的..e错在哪里/

偶觉得E好像改变句意了,当^^^^^的时候^^^^^^

文章是因果关系的唉