SC growth hormone

[Pandit]

Before scientists learned how to make a synthetic growth hormone, removing it painstakingly in small ammounts from the glands.

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 synthethic growth hormone, scientists had to remove it painstakingly

e) learning how to synthesize the growth hormone, it had to be painstakingly removed

[RonPurewal]

there's an enormous thread on this problem here.

if any of your questions are still unanswered after you read that thread, then go ahead and post the remaining questions on that thread.