But the main problem __________ deeper and will take longer to solve.

问题描述:

But the main problem __________ deeper and will take longer to solve.
A runs B stays C turns D grows
为什么选A,请给出详细的分析,

run deep 是固定短语, 意为“根深蒂固”“植根很深”“深藏不露”如: She's never shown any sign of having a mind of her own.Sill waters run deep. 她从不流露自己有什么想法.静水流深啊.And sometimes our dif...