With too much noise outside ,the little boy can't _A_ doing homework.A.get down to B.fix his attention to 为什么不能选B?我觉得从意思上来说,选B更通一些呢.难道B的语法错误?

With too much noise outside ,the little boy can't _A_ doing homework.A.get down to B.fix his attention to 为什么不能选B?我觉得从意思上来说,选B更通一些呢.难道B的语法错误?
With too much noise outside ,the little boy can't _A_ doing homework.
A.get down to B.fix his attention to
为什么不能选B?我觉得从意思上来说,选B更通一些呢.难道B的语法错误?

With too much noise outside ,the little boy can't _A_ doing homework.A.get down to B.fix his attention to 为什么不能选B?我觉得从意思上来说,选B更通一些呢.难道B的语法错误?
get down to意为致力于,专心于
get down to + doing sth.着手做某事
只有A后doing加了ing
而Bfix his attention to 虽有集中精力的意思,但其后面加to do sth
懂了吗