频率
参考答案:
质点在一秒钟内振动的次数,叫做振动频率.用字母f表示,它的单位为Hz(赫芝).
(1)猜想促使蜜蜂飞向花朵的因素。
猜想一:蜜蜂飞向花朵,跟花朵的大小有关;
猜想二:蜜蜂飞向花朵,跟花朵的 有关;
猜想三:蜜蜂飞向花朵,跟花朵的气味有关。
(2)试验步骤(填写空缺的步骤与数据):
China's badminton superstar Lin Dan won a thrilling final for his fifth world champion in Guangzhou on Sunday over Lee Chong Wei, who ______ his game due to injury.
A.concerned
B.recovered
C.abandoned
D.recognized