急に => quickly; immediately; hastily; suddenly; abruptly; unexpectedly ~ N4
昼となく夜となく => day and night N1
Continuous
に行く/に来る/に帰る => go/arrive/go back (to do something) N5
へ => Go to N, head to N , Often followed by verbs like 行く/いく, 来る/くる, 向かう/むかう… N5
Particles