— I'm really confused on how to balance my interest and study.

— Well, turn to your teacher for advice, in my opinion, _____ you'll make it. [ ]

A. but

B. and

C. so

D. unless

近期，国内IT市场上推出一款“苹果皮”产品，它的功能是将iPodTouch转型为具备电话、短信和GPRS上网功能（在调试中）的iPhone手机。而价格仅约为iPhone手机一半，深受消费者的欢迎。这段材料说明了（）

①知识创新需要对已有知识的扬弃②知识创新是已有知识积累的量变

③知识创新需要新思路、新方法④知识创新需要与旧知识彻底决裂

A.①③

B.②③

C.②④

D.①④