Question

Lucy and Lily often go to the zoo ________．

1. A.
   by a bike
2. B.
   on bikes
3. C.
   by the bike
4. D.
   on their bikes

Answer 1

D
“by+交通工具”表示乘坐某种交通工具，表交通工具的名词并不需任何的限定词或修饰词，名词也用复数，但若要加限定词或其他修饰语，则不用介词by．