把句子补充完整。

①春天里，小鸟们                                                                                    。

②春天像                                                                                    。​

（Ⅰ）求C；

（Ⅱ）若c= $\sqrt{7}$ ，△ABC的面积为 $\frac{3\sqrt{3}}{2}$ ，求△ABC的周长．

根据短文内容，选择正确答案。

    Radio, telephone and TV are widely used in the world. When you turn on the radio, you can listen. But when you use telephone, not only can you listen to others but also you can chat with them, however, you can't see anything at all. TV is much better than both of them. People can watch TV and listen to it, but they can’t take part in what they see.

    Today, some people are using a type of telephone called vision-phone（可视电话）. With it, two people who are talking can see each other. It is better than radio, telephone or TV.

    Vision-phones can be of great use when you have something to show the person whom you are calling. It will be helpful in people's life. Some day you may be able to call up a library and ask to read a book on your vision-phone. You may be able to do some shopping too. Perhaps in the future, people will use vision-phone.

选择恰当的词语填在横线处。

        这时我听到故乡在____(召唤   呼唤   呼喊)我,故乡有一种声音在____(召唤  呼唤   呼喊)着我。她低低地____(召唤  呼唤  呼喊)着我的名字,声音是那样的急切，使我不得不回去。