The boy is good at math.=The boy is ---- ----math.=The boy is ---- ----math.

问题描述:

The boy is good at math.=The boy is ---- ----math.=The boy is ---- ----math.
=The boy is ---- ---- ----math.=The boy ---- ---- ----math
额 打错了 是bad at math~……

poor in,
does badly in