【简答题】请用一个动词替代下面句子中括号中的动词短语,增加行文的正式度。 Scientists are ( looking into) innovative drug delivery systems that can transport and deliver a drug precisely and safely to its site of action.
【单选题】Conceived when he was in college and now in its 28th year of operation, Smith's exquisite brainchild has become the standard for door-to-door package delivery.