书面表达。

     假设你是Betty，你有个外国笔友叫Linda，她准备来中国旅游，不知道去北京好还是上海好，请你给她回一封E-mail，推荐她来北京旅游并说明理由，同时给她提一点游览这个城市的建议。开头和结尾已经给出，但不计人总词数，词数在60左右。

     理由：1. 北京是中国的首都；

                 2. 北京是有着悠久历史的古城；

                 3. 北京有很多名胜古迹：北京胡同、颐和园、故宫、长城、 * * 广场等等。

                 4. 中国人很友好，食物也很可口。

     建议：北京游客很多，务必先在网上预订好宾馆。

     Subject: Traveling in China

Dear Linda,

     Glad to get your E-mail. You told me that you wanted to visit China. Welcome to China.

     Now I'll give you some suggestions.                                                                                                     

     I think you'll have a good time !

                                                                                                                                 Yours,

                                                                                                                                  Betty

______ from space, the earth is blue.

[      ]

A. When seeing

B. When see

C. When we see it

D. When to see