24-34 Studying the fruit fly, a household nuisance but a time-honored experimental subject, has enabled the secrets of how embryos develop to begin to be unraveled by scientists.

A) Studying the fruit fly, a household nuisance but a time-honored experimental subject, has enabled the secrets of how embryos develop to begin to be unraveled by scientists.

B) By the study of the fruit fly, a household nuisance and also a time-honored experimental subject, it was possible for the secrets of how embryos develop to begin to be unraveled by scientists.

C) By studying a household nuisance but a time-honored experimental subject, the fruit fly enabled scientist to begin to unravel the secrets of how embryos develop.

D) By studying the fruit fly, a household nuisance and also a time-honored experimental subject, the secrets of how embryos develop are beginning to be unraveled by scientist.

E) The study of the fruit fly, a household nuisance but a time-honored experimental subject, has enabled scientist to begin to unravel the secrets of how embryos develop.

答案：E

请问其他选项被排除的原因之一是否是这几项中study动作的执行者错误呢？

如果 D 改成

By studying the fruit fly, a household nuisance but a time-honored experimental subject, scientist begin to unravel the secrets of how embryos develop.

是否就比E更好呢？

如果D是你改过的，估计就要选D了，呵呵