在用例建模的过程中，若几个用例执行了同样的功能步骤，这时可以把这些公共步骤提取成独立

—Do you think it is hard for you to learn math well?

—Yes. I really want to drop it.

A．go on learning well

B．pick it up

C．give it up

D．work hard at it

“Can you teach me how to sing the song  YOU AND ME ?”  “_________”

A．No problem.

B．No, I can’t.

C．I don’t have time .

D．That’s OK.

智力技能的特点有：动作对象的______，动作进行的______，动作结构的______。

第一在线炉点火步骤？