We tried to keep a （）, but he looked so ludicrous.

单项选择题（）is called erosion (侵蚀).

A．Land which wears away,
B．The wearing away of land
C．To wear away land
D．Wearing away land

单项选择题We do not permit （）in the office, so we do not permit him（）_ here.

A．to smoke; to smoke
B．smoking; to smoke
C．smoking; smoking
D．to smoke; smoking