情景对话

A：Would you like to have dinner with me this evening, Bob? 

B： ____ . Maybe another time.

A：What are you doing?

B：I'm making aplan____

A：What plan? Is it very important?

B：Yes, I always do volunteer work on the first Saturday of every month.

A：____

B：I help out at the children's hospital. I help to plan some activities.

A：____

B：Of course. You should help to make the sick children happy.

A：____ I can tell them some interesting stories.

a. Oh, I'd love to do that.

b. I must finish it on time.

c. Sorry, I can't. I'm busy.

d. Err…Bob, could I join you?

 e. What kind of volunteer work do you do？

已知 $\Delta ABC$ 的三边长分别为： AB= $2\sqrt{a^2+576}$ ，BC= $\sqrt{a^2+14a+625}$ ，AC= $\sqrt{a^2-14a+625}$ ，其中a>7．则 $\Delta ABC$ 的面积为____．

已知抛物线$y^2=4x$的焦点$F$与椭圆$\frac{x^2}{a^2}+\frac{y^2}{b^2}=1\left(a>b>0\right)$的一个焦点重合，它们在第一象限内的交点为$T$，且$TF$与$x$轴垂直，则椭圆的离心率为（   ）