blithe

她哼着欢快的歌谣，在花园里轻快地跳舞。

She danced around the garden, singing a ___blithe little tune.

他对朋友遇到的困难表现出一副漫不经心的样子，让人很不舒服。

His ___blithe attitude toward his friend's troubles made everyone uncomfortable.

她继续无忧无虑地疯狂购物，信用卡账单却在书桌上堆了一摞，一封都没打开过。

She continued her ___blithe spending spree even as the credit card bills piled up unopened on her desk.