He soon received promotion, for his superiors realized that he was a man of considerable （）.

单项选择题The European Union countries were once worried that they would not have （） supplies of petroleum.

A．proficient
B．efficient
C．potential
D．sufficient

单项选择题We'd like to （）a table for five for dinner this evening.

A．preserve
B．retain
C．reserve
D．sustain