Here is a working solution that was developed
for (var i = 0; i < Lines.Length; i++) {
Builder.Append(Lines[i]);
if (Lines[i].EndsWith(" and") || Lines[i].EndsWith(" of") ||
Lines[i].EndsWith(" for") || Lines[i].EndsWith(" at") ||
Lines[i].EndsWith(" the")) {
if (i < (Lines.Length - 1)) {
Builder.Append(" ").Append(Lines[i + 1]);
i++;
}
}
Builder.AppendLine("");
}
return Builder.ToString();
solved Merging Lines of text where string ends in a specific condition