一个m、两个d和g，三n、四p、十个t。(swim)、(nod、rid)、(dig、beg)、(run、win、begin)、(dip、drop、mop、stop)、(sit、hit、fit、set、get、let、put、regret、forget、pat)。
常见双写ing单词
cut-cutting
sit-sitting
swim-swimming
permit-permitting
stop-stopping
drop-dropping
perfect-perferring
dig-digging
win-winning
run-running
put-putting
begin-beginning
get-getting
plan-planning
admit-admitting
