题干
Finish your homework first,and then you'll watch TV for an hour.
A：can
B：be able to
C：able to
D：could
答案(点此获取答案解析）
B
Finish your homework first,and then you'll watch TV for an hour.
A：can
B：be able to
C：able to
D：could
在曲线
上移动，设点
，则