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 |