Both of his parents died of illness so he             support his family at the age of 14. [ ]

A. must

B. should

C. could

D. had to

读“天气系统图”，下列说法正确的是                                

A．该图为北半球气旋  

B．当亚欧大陆受此气压控制时，是北半球的夏季

C．我国长江中下游地区出现    

D．该图控制下多阴雨天气