帮我看看两道英语单选～ItisreportedthattheAirForceabout000000ayear.Reallyaproblem,isn'tit?AbirdhitcostBbirdshitcostCbirdhitscostDbirdhitcosts答案是CB为什么不行?2．Shipsmusthavemorethanoneredio

Question

帮我看看两道英语单选～
It is reported that____the Air Force about 000000 a year.Really a problem,isn't it?
A bird hit cost B birds hit cost
C bird hits cost D bird hit costs
答案是C B 为什么不行?
2．Ships must have more than one redio operator_______someone is always awake to recieve message 24 hours.
A if B since C while D So
答案是C WHY?

Answer 1

第一题：
从语言学的知识来讲,bird hit是一个合成词(compound word),分析它的深层结构,hit是它的中心语(head),bird是hit的修饰成分(modifier),这类词在变复数的时候只把中心语变成相应的复数就可以了.
第二题：
根据后面出现了always,从语义的角度可以排除A、B两项；while是表并列关系,一般表示前后两个条件同时存在、同时满足,或者表示同时存在的两个状态的对比关系.而so用来表示因果关系,此题中more than one operator和one is always awake不存在因果关系（前者不能必然导致后者）,而是并存的（或者说逻辑上的“且”的）关系.所以选while.