单项选择题 下列烯烃与HX加成的活性最快的是
单项选择题 盐酸吸收塔的液位要求控制在0.2-1.5m之间,因为盐酸吸收塔渗漏,正常生产时吸收塔液位控制在()
单项选择题 Delivery (or delivery) process. This is the end operation of the distribution center, and also an important part of the whole distribution process. It includes ( ) two economic activities. A. Packaging and loading B. delivery and collection C. loading and delivery D. inventory and delivery