attend classes / attending classes / go to school / attending school / going to school / attend school

be well acquainted with / have a thorough knowledge of / be versed in / be at home in / be well posted about

hitting *someone hard / crack down on / make a heavy attack on *someone / strike *someone severely / hit *someone hard / making a heavy attack

have relations with / associate with / hold intercourse with / keep company with

keep company with / have relations with / associate with / hold intercourse with

navigate / sail

go down a road / going along a road / going down a road / go along a road

be widely accepted / being popular usage / be done widely / being popular / being done generally / be done generally / be used commonly / being widely accepted / be popular / normal activity / being used commonly / being done widely / be in popular usage

regret deeply / sorrow deeply

adding up / tallying / sum up / amount / total / tally / add up