【单选题】关于青蒿素和双氢青蒿素(结构如图)的下列说法,错误的是______。 A.青蒿素的分子式为C15H22O5 B.由青蒿素制备双氢青蒿素的反应属还原反应 C.青蒿素分子中含有过氧链和酯基、醚键 D.双氢青蒿素分子中有2个六元环和2个七元环
【单选题】The service in this restaurant is very poor there are not enough waiters to wait ______ customers.
【单选题】青蒿素结构中含有(),具有氧化性,酸性条件下能将碘离子氧化成碘与淀粉指示液显蓝紫色
【简答题】青蒿素结构中含有(),遇碘化钾试液氧化析出(),加淀粉指示剂,立即显()。
【单选题】In this restaurant, there are not enough waiters to wait ______ customers.
【单选题】One of the waiters _________ my uncle.
【单选题】( )安装在自动变速器输出轴附近。它是一种电磁感应式转速传感器,用于检测自动变速器输出轴的转速。ECU根据车速传感器的信号计算出车速,作为其换档控制的依据。
【简答题】[A]visitors[B]owners[C]waiters[D]guests
【单选题】Most of the waiters are ______ in their work because the owner of the restaurant does not pay them on tinge.