三个短语造句.初二下学期的水平.不要太复杂了.1.work out 2.afford 3.come up with

I can't work out the math problem .
My parents said they can afford me to study .
I came up with a good idea .

they finally worked out the problem after 3 hours' discussion三小时的讨论后他们解决了问题
she can't afford this expensive pair of shoes她买不起这双很贵的鞋子
they came up with the idea when they finished the book读完书后，他们想到了这个主意

I can work out this problem by myself.
I can't afford it.
I want to come up with other students.

I work out this difficult problem.
I can not afford to buy a car.
I had to run to come up with her.