He started _____ football when he was 15. [ ]
A. to playing
B. play
C. to play
答案:C
—The twins will fly to New York with their parents this evening?
---No.In fact, their plane ___ from Shnaghai ahead of time.
A.has taken off
B.will take off
C.is taken off
D.is being taken off
关于电源电动势的说法,正确的是
A.电源的电动势大小等于路端电压
B.电源的路端电压增大时,其电源电动势一定也增大
C.无论内电压和外电压如何变化,其电源电动势一定不变
D.一节新干电池的电动势为1.5 V