______ discovered liquid fuel as a fuel for rockets.

A.having some early art training.
B.attending the best primary and middle schools.
C.getting a good job.
D.the parents’ prestige and position.

A.husbands, wives enjoy their family life after retirement age
B.husbands, wives find they are strangers after retirement age
C.husbands’ and wives’ poor physical condition
D. husbands and wives are prosperous after World War Ⅱ