[問題]PP test2 Q36 (structure)

[wasibenny]

36. When _______ with atmospheric particles, they create many types of secondary particles, including positrons, mesons, and hyperons.
A. the collision of primary cosmic rays
B. primary cosmic rays collide
C. primary cosmic rays colliding
D. do primary cosmic rays collide

答案是B
想請問為什麼collide不用加ing....@@


謝謝～

[spain]

36. When _______ with atmospheric particles, they create many types of secondary particles, including positrons, mesons, and hyperons.
A. the collision of primary cosmic rays
B. primary cosmic rays collide
C. primary cosmic rays colliding
D. do primary cosmic rays collide

答案是B
想請問為什麼collide不用加ing....@@


謝謝～

試著回答一下...
When是conj.，rays是主詞，collide是動詞...