a person who keeps their skills or plans secret until an important moment
एक व्यक्ति जो अपनी क्षमताओं या योजनाओं को एक महत्वपूर्ण क्षण तक गुप्त रखता है (ek vyakti jo apni kshamataon ya yojnaon ko ek mahatvapurn kshan tak gupt rakhta hai)
"Nobody expected her to win; she was a dark horse."
"किसी ने नहीं सोचा था कि वह जीतेगी; वह थी एक गुप्त प्रतियोगी।" (kisi ne nahi socha tha ki wah jeetegi; wah thi **ek gupt pratibandhi**.)
to suddenly start laughing loudly
to transfer responsibility or control to someone else
to be very thankful about something
to undergo a significant change or improvement
to fix small problems or errors
to succeed in understanding something difficult or strange