单项选择题
A.dwell on
B.come upon
C.base on
D.draw upon
单项选择题 How much of your country's electrical supply is ()from water power
单项选择题 In order to prevent stress from being set up in the metal, expansion joints are fitted which ()the stress by allowing the pipe to expand or contract freely.
单项选择题 Weeks ()before anyone was arrested in connection with the bank robbery.