08年10月SAT语法提问

08年10月SAT语法提问
(Chad wore his hat just as his favorite old movie stars did when perched on the back of his head.)
A. Chad wore his hat just as his favorite old movie stars did when perched on the back of his head.
B. Chad wore his hat perched on the back of his head,jist as his favorite old movie stars did.
答案是B,为什么A不对?
A soft lullaby and the drumroll of thunder during a summer storm are but two of the diverse sounds (that can be perceived by the human ear).
A.that can be perceived by the human ear
E.that they can perceive with the human ear
答案是A,为什么E不对?
In 1980 a scholar who (was examining) a fifteentheentury letter-writing manual (discovering) (fragments from) love letters (exchanged) between a famous twelfth-century couple,Abelard and Heloise. (No error)
答案是B,为什么不是A?in 1980是时间段吗?