- あんなにひどいこと言いわれたら、怒おこるのも当然とうぜんだよ。

anna ni hidoi koto iwaretara, okoru no mo touzen da yo.

After being told something that awful, of course you'd get angry. casual

- 準備じゅんびもせずに試験しけんを受うけたのだから、落おちたのも当然とうぜんだ。

junbi mo sezu ni shiken o uketa no dakara, ochita no mo touzen da.

Since he took the exam without even preparing, it's only natural that he failed. neutral