【题目】_______ will do good to patients to follow the advice of doctors, because they're professional.
A.They
B.It
C.As
D.That

【答案】B
【解析】句意：听从医生的建议对病人有好处，因为他们是专业的。句中It作形式主语，不定式to patients to follow the advice of doctors做真正主语。故选B。