题干
She did what she could _______ us. Though 3,000 dollars is a lot of money for her.
A：help
B：helped
C：helping
D：to help
答案(点此获取答案解析）
D
She did what she could _______ us. Though 3,000 dollars is a lot of money for her.
A：help
B：helped
C：helping
D：to help
的部分图象如图所示，则
的图象可由函数
的图象（纵坐标不变）变换如下