目前我国水土流失十分严重，大约有180平方千米的水土流失面积。读图完成下列要求。

猜想一：琴弦发出声音的音调高低，可能与琴弦的横载面积有关；

猜想二：琴弦发出声音的音调高低，可能与琴弦的长短有关；

猜想三：琴弦发出声音的音调高低，可能与琴弦的材料有关；

为了验证上述猜想是否正确，他们找到了上表所列9种规格的琴弦，因为音调高低取决于声源振动的频率，于是借来一个能够测量振动频率的仪器进行实验．

已知$\sin {10}^{°}=k$，则$\sin {70}^{°}=$（   ）

    There is a woman ____（name）Daisy who has devoted all her life to ____（attend）to the homeless children. It's generally recognized that what she has done for children ____（deserve）to be respected by everyone. ____（personal）speaking, her selfless behavior sets a good example to us.

    There was a time when I came across Daisy who ____（invite）to deliver a speech, during which she indicated, “____（take）care of homeless children is just ____ ordinary job, but it doesn't mean that you can look down ____it. Every job is equal. We can't say which one is ____（good ）.” She also said, “Once you set out to do something, you ought to carry on with it to the end, ____ you will gain nothing in the end.”

$\left(\frac{6}{35}+\frac{4}{21}\right)÷\frac{4}{7}$ =____