"Not once has our neighbour invited us into his house".
A
Our neighbour has invited us into his house not once but many times.
B
Our neighbour has never invited us into his house .
C
Occasionally our neighbour has invited us into his house .
D
Our neighbour has not always invited us into his house .
Correct Answer: Our neighbour has never invited us into his house .
Negative adverb (যেমন not once ) দ্বারা বাক্য শুরু হলে inversion হয় অর্থাৎ verb + subject হয়। Not once থাকায় বাক্যটির অর্থ negative হবে। তাই সঠিক উত্তর (খ)।