A: Hello, Mike.

B: Hello , John. ____.

A: I'm drawing pictures . ____.

B: I'm writing a letter .____.

A: No, I didn't. I was at home .

B: Tomorrow is Sunday .let's go to climb the mountains .

A: ____.

B: What are you going to take?

A: ____

B: Me, too

A: What time shall we go ?

B: Let's go at half past seven .

A: OK！

函数y=cos2x在点$\left(\frac{\pi }{4},0\right)$处的切线方程是（  ）

想一想，写一写。

    鸦片战争前后，外国资本主义对中国的冲击加剧，促使中国与西方世界的联系不断扩大。为了解西方，抵御外侮，一批先进中国人开始以新的眼光审视世界。