望而興嘆 [－－兴叹]

Jyutping mong6 ji4 hing1 taan3
Pinyin wàng ér xīng tàn

Definitions (CC-CEDICT)
  1. to look and sigh
  2. to feel helpless
  3. not knowing what to do
Definitions (Wiktionary)
  1. phrase, idiomatic
    to look and sigh; to feel helpless; not to know what to do