半纵向调查是指在某一地区范围内选择有代表性的对象，在某一较短的时间内对某几项指标进行一次性大数量的调查。()

A. sought
B. sent
C. visited
D. needed

A. compensatory
B. comprehensive
C. complicated
D. compassionate

A. defend hurricanes
B. protect coastal cities
C. prevent terrorist attack
D. generate electric power