几道语法题

dongganeliUID: 2114332

1. Lillian D. Wald was an ardent (pacifist), and (participants) in peace movements (held) her in (big) regard.
2.Nebraska has floods in some years,_____
A. in others drought
B.droughts are others
C. while other droughts
D.others in drought
3.Algebra is the (branch) of mathematics concerned with operations on (sets) of numbers or other (elements) that are often represented (at) symbols.
4. The early (periods of aviation) in the United States was marked by (exhibition flights) made by (individual fliers) or by (teams of performers) at country fairs.

四道题的答案是D A D A
望高人指点

zfjansonUID: 191907

第一题我也感觉是C也，其它和楼上一样。