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His son should to help you.
They cannot do this exercise yesterday.
You ought have told us about his arrival.
Must I take your dictionary for a while?
My children are able swim very well.

His son should help you.They couldn't do this exercise yesterday.You ought to tell us about his arrival.May I take your dictionary for a while?My children can swim very well.

1) His son should help you2) Thay coudn`t do this exercise yesterday.3) You ought to told us about his arrival.4) May I take your dictionary for a while?5) My children can swim very well.P.S. не уверен, но кажется так.