1.主语是the wealth单数
2.be likely to do > O be likely that>X
3.more...than > O more..rather than>X
4.the origin of birds at this stage 表達出 現今鳥類的起源 是語意錯誤 不應該置放在這裡
4.
D, A works as well as B at the prevention of C, B要补出谓语动词,否则会让人误解为 A works at the prevention of C as well as at the prevention of B
E, at preventing blood clots强调在preventing这个过程有效,应该用at the preventing或at the prevention,强调是对prevent的结果有效
attrition rate 是离职率?