时钟上，9点时时针与分针的夹角是（ ）。

句型转换，不改变原意。

1. This hotel is the best of all in the city. (不改变原意) 

    This hotel is better      __                           hotel in the city.

2. Playing the piano is not easy to learn. (不改变原意) 

       __    is not easy _      playing the piano.

3. Zhou Qiang doesn't run as fast as I do. (不改变原意) 

    Zhou Qiang runs _   __             _I do.

4. The boy doesn't do as well as the girl. (不改变原意) 

    The boy does _  _               _the girl.

5. All the runners start to run as soon as they hear the gun. (不改变原意) 

    All the runners start to run_____  _____  _____.

一般各种煤尘爆炸下限的最低值为（）

A、45g/m³

B、50g/m³

C、60g/m³

《北京人》发表于（）年，作者巧妙地运用象征手法，以（）象征封建阶级的灭亡。

解放军某部有600人，他们排成四路纵队，每相邻两排之间前后相距1米，队伍每分钟行75米，现在要通过一座长676米的桥，从排头上桥到排尾离桥需多少分钟

A．9
B．10
C．11
D．12

以下是对中国文化艺术的文言别称，属于美术的是( )。

A．丝竹
B．墨宝
C．丹青
D．金石