六年目の疑惑の英語

an agony of doubt

The course of study extends over six years―spans six years.

a sneaking suspicion

trumped-up charges

a suspicious glance [look]

to harbour doubts

You will understand it as you grow older.

unfounded suspicions

interest at （the rate of） 6 percent per annum

to have a doubt

to harbour doubts―harbour suspicions

to admit of doubt

distrust

have a sneaking suspicion

the condition of becoming aged and feeble

I have my doubts.

the last work that one does for the year

hold in suspicion

feelings of doubt

I harbour doubts

of people, the condition of growing old

They have completed their course after five years of study.

a lean year

come under suspicion

arouse suspicion

think back over the past year

to harbour doubts―have one's doubts―suggest a doubt―（about anything）

to incur suspicion―excite suspicion

have doubts about

an insoluble doubt