阅读下面短文，按照句子结构的语法性和上下文连贯的要求，在空格处填入一个适当的词或者用括号中词语的正确形式填空。
Medical drugs sometimes cause more damage than they cure. One solution      this problem is to put the drugs inside      capsule, protecting them from the body—and the body from them—until they can be released at just the right spot. There are lots of ways to trigger (引发) this release,    (include) changing temperature, acidity, and so on. But triggers can come with      own risks—burns, for example. Now, researchers in California have designed      could be a harmless trigger to date: shining near-infrared light (NIR, 近红外线) on the drug in the capsule.
The idea of using light to liberate the drug in the capsule isn’t new. Researchers    the globe     (develop) polymers (聚合物) and other materials that begin to break down when they absorb either ultraviolet (UV, 紫外线) or visible light. But tissues also readily absorb UV and visible light, which means the drug release can be triggered only near the skin,    the light can reach the capsule. NIR light      (large) passes through tissues, so researchers have tried to use it as a trigger.      few compounds (化合物) absorb NIR well and go through chemical changes.