prep2-21

Before scientists learned how to make a synthetic growth hormone, removing it painstakingly in small amounts from the pituitary glands of human cadavers.

(A) scientists learned how to make a synthetic growth hormone, removing it painstakingly

(B) scientists had learned about making a synthetic growth hormone, they had to remove it painstakingly

(C) scientists learned how to synthesize the growth hormone, it had to be painstakingly removed

(D) learning how to make a synthetic growth hormone, scientists had to remove it painstakingly

(E) learning how to synthesize the growth hormone, it had to be painstakingly removed by scientists

C是正确答案

我选的是D，虽然make a synthetic growth hormone比较罗嗦，但用的是相同的主语

如果是

learning how to synthesize the growth hormone, scientists had to remove it painstakingly

语法对吗

从分词修饰角度来讲，D没错，但是错在逻辑意思，科学家不 painstakingly，而是从体内拿出荷尔蒙是 painstakingly

科学家只管synthesize,不可能是remove的主语，应该是"doctors" remove it。所以d错。

这个解释很好!!!!!!

(C) scientists learned how to synthesize the growth hormone, it had to be painstakingly removed

C中it指代growth hormone

(D) learning how to make a synthetic growth hormone, scientists had to remove it painstakingly

D中it指代a synthetic growth hormone，逻辑不合理