Keep it in mind not to disturb the president at two o’clock this afternoon, when he ____ a global joint meeting.
He argued ______ smoking, and insisted that it was ______argument that smoking was harmful to health.
The children were warned of not being too __________ about things they are not supposed to know.
Please don’t phone him between 1 and 3 p.m. tomorrow. He _________ a lecture then.
In a sport team each player has a clear role, and there are few occasions ______ members are confused or uncertain of their roles.
It is the test system, _____ the teachers, that is to blame for the heavy burden of middle school students nowadays.