.______ the beginning of the 19th century did scientists know that all matter is made up of atoms.

By the time I saw the angry expression onhis face, I ______ exactly what I was having to face. But not for a moment______ I should quit.

He________ the pencil and began to draw the beautiful surroundings on a sheet of paper.[ ]

Since the man had no choice but to fight back, we’d better _________ him.

Korea has always sought for a directtalk with the US, without China ________