【单选题】____ 是破坏性程序和计算机病毒的根本差异。
【单选题】To survive in the intense trade competition between countries, we must ______ the qualities and varieties of products we make to the world market demand.
【单选题】( )是破坏性程序和计算机病毒的根本差异。
【单选题】--- Have you told him we have changed the plan? I _____ have, but I haven’t done it yet.