17, 18. (a) Why can we be certain that Jehovah’s Witnesses are the ones who are preaching the good news of the Kingdom today?
١٧ ،‏ ١٨ ‏ (‏ أ )‏ مَاذَا يُثْبِتُ أَنَّ شُهُودَ يَهْوَهَ هُمْ مَنْ يَكْرِزُونَ بِبِشَارَةِ ٱلْمَلَكُوتِ ٱلْيَوْمَ ؟‏