1£®—What has made John look like lacking sleep?

—That he had to prepare for the coming exam and stayed up last night.

2£®What was the most important to her£¬she told me£¬was her family.

3£®It remains to be seen whether this plan is practical enough to keep the project going.

4£®It hasn't been made clear when the new underground line is to be open to traffic.It's maybe next year.