题目

The best and most-commonly used sources for the pills we have are oily fish like salmon（畦）， mackerel and sardines. Many environmentalists fear that some species are being over fished for this purpose. We may have an endless voracity for fish oil, but we don't have an endless supply of fish.Menhaden, which is described as “a big-headed, smelly, foot-long fish , is in great danger. Although prized for dinner in the 18th century, the species has become the unknown victim of the fish oil business 9 which presents us with potential sea fish. Menhaden filter-feed almost entirely on algae 下列关于实验操作的描述正确的是 A．实验剩余的药品放回原瓶B．将带火星的木条放在集气瓶口，检验氧气是否集满C．用酒精灯加热试管里的液体时，试管里的液体不应超过试管容积的12D．不小心碰倒酒精灯，洒出的酒精在桌上燃烧起来时，应 ．