What happened to Langley after World
War II.

As NASA began to grapple with the challenges of putting people in space, Langley contributed to the effort. Members of Langley's Pilotless Aircraft Research Division, formed after World War II to learn more about the transonic flight, were tapped to become members of the Space Task Group

what do u need with

the pronoun reference replaces a noun, but you have to make sure there's no room for confusion.

in the first sentence "her" could be referring to shely or to the sister. the answer there is "shelly called her sister and told her about the new baby."

in the second sentence "it" could be referring to the roof or the floor. the answer there is "since the roof leaks on the family room floor, we need to repair the roof."