21.   Yet nobody has yet offered another convincing explanation for the kinds of carbon that suddenly appeared in the atmosphere.

22.   If it is to be widely approved by the international community as an unavoidable step, however, the United States must offer a convincing explanation to the world.

23.   Iran could break ties with Britain if London failed to provide a convincing explanation over the alleged bugging of the Iranian embassy, MP Majid Naderi said Monday.

24.   Anyone discovered without papers is immediately suspicious and a summary lynching awaits those who cannot offer a convincing explanation.

25.   Spring resigned along with Reynolds after the premier failed to provide a convincing explanation for why the affair was at first covered up.