已知向量，满足 $\overrightarrow{a}·\left(\overrightarrow{a}-2\overrightarrow{b}\right)=3$ ，且 $\left|\overrightarrow{a}\right|=1$ ， $\overrightarrow{b}=\left(1,1\right)$ ，则 $\overrightarrow{a}$ 与 $\overrightarrow{b}$ 的夹角为（   ）

仿照下面例句写一句话，要求与例句格式相似，并运用比喻等修辞手法。
我不是挺立在高山峻岭中的巨松，而是辽阔草原上的一棵小草——为壮丽的河山添上一笔绿意。
仿句：                                                               

A: Betty, will we study at school in the future?

B: ____ But we don't use paper, pens or rulers.

A: What will we use?

B: ____

A: But will we use pencils in the art class?

B: ____ We will draw pictures on the computers.

A: ____ How long will we study at school every day?

B: I think we will study for about three hours and then we can play games.

A: Really?

B: ____ It's just my dream.

A: It's my dream too.

两个偶数相加，和是（    ）