4.Why does the woman plan to go to town?

A.To pay her bills in the bank.

B.To buy books in a bookstore.

C.To get some money from the bank.

3.What does the woman mean?

A.Cathy will be at the party.

B.Cathy is too busy to come.

C.Cathy is going to be invited.

2.Where are the speakers?

A.In a restaurant.

B.In a hotel.

C.In a school.

200．向量的垂直

非零复数，对应的向量分别是，，则

　 的实部为零为纯虚数

　(λ为非零实数).

199．复平面上的两点间的距离公式

(，).

198．复数的乘法的运算律

对于任何，有

交换律:.

结合律:.

分配律: .

197．复数的四则运算法则

(1);

(2);

(3);

(4).

196．复数的模(或绝对值)

==.

195．复数的相等

.()