短文填空。

                                                     Welcome to the River District

     Turn right on River Avenue and enjoy the city's quiet streets, clean rivers   _1_   nice parks.   _2_   a

walk through the park on River Avenue. Next to the park is an old hotel. Across   _3_   the hotel is a big

and beautiful school. There is a   _4_   near the school.

     Susan works in the shop   _5_   a shop assistant. She loves living here and she works very hard. She

goes to   _6_   early(早) every day. There are always lots of students in the shop, so she is very busy. She gets back home very   _7_  , usually   _8_   ten o'clock in the evening. She feels tired   _9_   she loves her job very much, because she thinks it is interesting and she can work with students.  

     Susan is very kind and she likes helping others.   _10_   you come to visit the River District, you can

find her. And she will be your tour guide (导游).

下列现象中，说明燃着的气体是CO的是（　　）

A．火焰呈淡蓝色，扣干冷烧杯，杯壁有水珠，倒入澄清石灰水，石灰水不变浑浊

B．火焰呈蓝色，扣干冷烧杯，杯壁无水珠，倒入澄清石灰水，石灰水变浑浊

C．火焰呈苍白色

D．火焰几乎无色