补全对话
Amy: Hello, Lingling. ____ is Amy speaking.
Lingling: Hello, Amy.
Amy: ____ are you?
Lingling: I am ____. Thank you.
Amy: ____ you at home yesterday?
Lingling: No, I wasn't. I was____with Sam.
Amy: Were you at the zoo?
Lingling: Yes, we were.
如图所示是几种声音输入到示波器上时显示的波形,其中音调相同的是____ ;响度相同的是____ 。
求证:
张阿姨洗衣服,已知以下信息:①洗衣机的洗衣缸内可容纳洗衣水(洗衣水指水与洗衣粉的混合液)和衣服共20千克;②洗衣缸内已有衣服5千克,洁净牌洗衣粉两匙;③每匙洗衣粉约0.02千克;④每千克洗衣水中含有4克洁净牌洗衣粉洗衣效果最好。问:要使洗衣水效果恰好,张阿姨还需往洗衣缸内加多少洗衣粉,添多少水?