对于动物细胞和植物细胞的比较，下列哪些正确？（） ["动物细胞缺乏细胞壁，植物细胞有细胞壁","动物细胞无叶绿体，植物细胞必有叶绿体","动物细胞有中心粒，植物细胞没有中心粒","动物细胞有线粒体，植物细胞无线粒体","动物细胞无液胞，植物细胞有大液胞"]
依照行政复议法第二十条的规定，上级行政机关认为行政复议机关不予受理行政复议申请的理由不成立的，可以先行督促其受理；经督促仍不受理的，应当责令其限期受理，必要时也可以（）；认为行政复议申请不符合法定受理条件的，应当告知申请人。 ["命令其受理","代理受理","直接受理","变更受理部门"]
双向沟通理论的中心内容是什么？
It is essential for（）to give a complete description of damage and shortage in the discharging report. ["the office staff","the terminal staff","the ship's crew","the insurance company"]
Condensate must be drained from the intercooler and after-coolers of an air compressor because （）. ["the cooling effect of the condensate reduces the compressors efficiency","a danger of explosion exists whenever water is present in a compressor","water causes erratic operation of pneumatic components","the volumetric capacity of the first stage is reduced if water remai"]
什么是收缩蛋白学说？
