"Be still, sad heart! and cease repining;

Behind the clouds is the sun still shining;
Thy fate is the common fate of all,
Into each life some rain must fall,
Some days must be dark and dreary."

1: from the context, From the context, what do you conclude is the probable meaning of repining in the poem?
A: expressing uncertainty
B: expressing determination
C: expressing happiness
D: expressing unhappiness****