题干

小明在做“探究浮力大小”实验中,测得装满水的溢水杯中水的深度为20cm,空小桶重力为0.3N,把它们放在水平桌面上,如图甲所示.再将一个重为0.5N小球轻轻放入溢水杯中,小球沉到杯底,溢出的水全部流入小桶,如图乙所示.将装有溢出水的小桶挂在弹簧测力计下,静止时测力计的示数如图丙所示.

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    In early spring, the changing temperature usually makes a number of Chinese people uncomfortable. Cold air, bringing rain or even snow, easily tears up(破坏) the warmth of the spring within a night(一夜之间).

    However, with the coming of Guyu-the Grain(谷物) Rain, the blue sky and gentle winds would finally stay. Falling usually on or around April 20 every year, Guyu is the sixth of the 24 solar terms(节气). It means the beginning of a lively summer and people get busy from now on.

    Sow(播种) grains

    This is an important period of the growth of grains. The ancient Chinese already knew that as Guyu comes, the weather will become warm enough for sowing. The farmers usually catch the chance to plant rice, corn and beans.

    Hope for safety and harvest

    For those living near the sea, they will hold some ceremonies(仪式) on Guyu, hoping for safety as well as harvest during the coming fishing season.

    Watch the peony

    It's also a great time to see the peony(牡丹), which is known as “the Queen of All Flowers” in Chinese culture. As a result, watching peonies becomes one of the most enjoyable activities for many. The flower is said to be the favourite of Empress(女皇) Wu Zetian of the Tang Dynasty, who was the only woman ruler in Chinese history.

    Pick tea leaves

    Tea leaves picked before Guyu are among the best tea leaves. People believe that the tea leaves picked on the day of Guyu can make eyes clear and drive away bad luck. So the habit of drinking tea at this time of year has become a tradition in some places of China.