他整个周末都在埋头苦干地做那个复杂的数学作业。

He spent the whole weekend ___slogging through that complicated math assignment.

我们顶着烈日，在沙滩上艰难地前行。

We were ___slogging through the hot sand under the scorching sun.

工人们正在用锤子反复敲打那块金属。

The workers were ___slogging at the metal piece with hammers repeatedly.