The old professor has such a bad memory that he looks for the watch while he is ___.
Eugene’s never willing to alter any of his opinions, so it’s no use ________ with him.
Up till now we _______ four units and this will be the second time that we _______ a test.
Charlie ______ be really difficult at times even though he’s a nice person in general.
It was only after I came across that matter_______ how important it was to master a foreign language.
--- When shall we meet again, Tom? --- Make ______ day you like; it’s all the same to me.