某学生量取液体，视线与液体凹液面的最低处保持水平，读数为30 mL，将液体倒出一部分后，俯视读数为20 mL，则该同学实际倒出的液体体积为 （）                 

电动机是将电能转化为机械能的设备，下列使用了电动机的电器是（   ）

让她为装有萌发种子的密闭玻璃瓶，瓶口用材料密闭，瓶中插入一支温度计，能反映瓶内温度随时间变化的曲线是（   ）

阅读短文，判断正误。
    Hello, friends! Let's go on a trip to Beijing. Beijing is the capital city of our country. It's in the north of China. There is a big square in this city. Do you know its name? Its name is Tian'anmen Square. In Beijing, you can see the Bird's Nest(鸟巢). The 2008 Olympic Games were held in it. And you can see some old buildings, such as the Palace Museum. The Great Wall is also very famous in China. It's very old and long.

1901年清政府与帝国主义签订哪一个条约之后，使中国完全陷入半殖民地半封建社会的深渊之中（   ）