Our country are working even harder now to _______ the gap between the developed countries and ours.
It is general believed that teaching is ________ it is a science.
________ by the beauty of nature, the girl from London decided to spend another two days on the farm.
What surprised me was not what he said but ________ he said it.
________ with the size of the whole earth, the biggest ocean does not seem big at all.
He speaks English well indeed, but of course not ________ a native speaker.